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  • Articles  (144)
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  • biodegradation  (144)
  • Springer  (144)
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  • Energy, Environment Protection, Nuclear Power Engineering  (144)
  • 1
    Electronic Resource
    Electronic Resource
    Isolation of Fenitrothion-degrading Strain Burkholderia sp. FDS-1 and Cloning of mpd Gene (2006)
    Springer
    Biodegradation 17 (2006), S. 275-283 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; Burkholderia ; fenitrothion ; mpd gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A short rod shaped, gram-negative bacterium strain Burkholderia sp. FDS-1 was isolated from the sludge of the wastewater treating system of an organophosphorus pesticides manufacturer. The isolate was capable of using fenitrothion as the sole carbon source for its growth. FDS-1 first hydrolyzed fenitrothion to 3-methyl-4-nitrophenol, which was further metabolized to nitrite and methylhydroquinone. The addition of other carbon source and omitting phosphorus source had little effect on the hydrolysis of fenitrothion. The gene encoding the organophosphorus hydrolytic enzyme was cloned and sequenced. The sequence was similar to mpd, a gene previously shown to encode a parathion-methyl-hydrolyzing enzyme in Plesiomonas sp. M6. The inoculation of strain FDS-1 (106 cells g−1) to soil treated with 100 mg fenitrothion emulsion kg−1 resulted in a higher degradation rate than in noninoculated soils regardless of the soil sterilized or nonsterilized. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide waste in the environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10532-005-7130-2
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  • 2
    Electronic Resource
    Electronic Resource
    The Impact of Bioaugmentation on Metal Cyanide Degradation and Soil Bacteria Community Structure (2006)
    Springer
    Biodegradation 17 (2006), S. 207-217 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; DGGE ; K2Ni(CN)4 soil bacterial populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Metal cyanides are significant contaminants of many soils found at the site of former industrial activity. In this study we isolated bacteria capable of degrading ferric ferrocyanide and K2Ni(CN)4. One of these bacteria a Rhodococcus spp. was subsequently used to bioaugment a minimal medium broth, spiked with K2Ni(CN)4, containing 1 g of either an uncontaminated topsoil or a former coke works site soil. Degradation of the K2Ni(CN)4 was observed in both soils, however, bioaugmentation did not significantly impact the rate or degree of K2Ni(CN)4 removal. Statistical analysis of denaturing gradient gel electrophoresis profiles showed that the topsoil bacterial community had a higher biodiversity, and its structure was not significantly affected by either K2Ni(CN)4 or bioaugmentation. In contrast, profiles from the coke works site indicated significant changes in the bacterial community in response to these additions. Moreover, in both soils although bioaugmentation did not affect rates of biodegradation the Rhodococcus spp. did become established in the communities in broths containing both top and coke works soil. We conclude that bacterial communities from contaminated soils with low biodiversity are much more readily perturbed through interventions such as contamination events or bioaugmentation treatments and discuss the implications of these findings for bioremediation studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10532-005-4219-6
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation and identification of thiocyanate utilizing chemolithotrophs from gold mine soils (2003)
    Springer
    Biodegradation 14 (2003), S. 183-188 
    Details
    ISSN: 1572-9729
    Keywords: 16S rDNA ; biodegradation ; Biolog ; Klebsiella ; thiocyanate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A mixed bacterial culture capable of growing in potassium-thiocyanatecontaining medium (200 mg KSCN) has been isolated from bacterial suspensions of soilsamples collected near gold mines in Kumjung (Korea). The isolates were initially characterized by metabolic profile analysis and were identified as Bacillus thermoglucosidasius,Bacillus cereus, Bacillus licheniformis, Bacillus mycoides, Brevibacteriumepidermidis, Brevibacterium otitidis, and Corynebacterium nitrilophilus.One of the seven isolates was initially characterized as Brevibacterium epidermidis,which is not known to degrade thiocyanate. However, using 16S rDNA sequencing, thisstrain was identified as a member of Klebsiella. The strain shows high similarityvalues (95.8 to 96.4%) with Klebsiella species, and the closest known relative was foundto be K. ornithinolytica ATCC 31898. The result indicates that species of the genusKlebsiella were the closest phylogenetic relatives of the investigated strain. This isthe first known report of a member of Klebsiella that is capable of utilizing thiocyanate assole source of carbon and nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1024256932414
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  • 4
    Electronic Resource
    Electronic Resource
    Adsorption/Desorption of Polyvinyl Alcohol on Solid Substrates and Relevant Biodegradation (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 67-79 
    Details
    ISSN: 1572-8900
    Keywords: Polyvinyl alcohol ; biodegradation ; soil, clay ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The rates and extents of absorption and desorption of polyvinyl alcohol (PVA) samples on different solid substrates comprising montmorillonite, quartz sand, and farm soil, as well as humic acid mixture are reported. The uptake of PVA by the substrates was analyzed as a function of PVA hydrolysis (72–98%), molecular weight, and molecular weight distribution. Higher adsorption was detected on montmorillonite followed by farm soil, whereas the quartz sand did not display any specific adsorption affinity for the PVA. An increase in the hydrolysis degree of PVA increased the adsorption rate and extent whereas this feature was reversed by an increase in PVA molecular weight. The desorption of PVA samples from the different substrates was performed both under various pH conditions and in the presence of concentrated HF that was used to dissolve the silicon derivatives present in the substrates. Biodegradation experiments carried out in liquid cultures of PVA adsorbed on montmorillonite showed that the mineralization of the adsorbed PVA was much lower than that detected for the nonadsorbed PVA. This investigation suggests that irreversible adsorption of PVA on the clay component occurs in soil, thus substantially inhibiting PVA biodegradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011569920349
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  • 5
    Electronic Resource
    Electronic Resource
    Degradation Kinetics of Biodegradable Fiber Composites (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 91-96 
    Details
    ISSN: 1572-8900
    Keywords: Polyester amide ; hemp fiber ; composite ; biodegradation ; carbon balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In a composite, fast degradable fibers determine the degradation of the slowly degradable matrix. Such biodegradable composites consisting of degummed hemp fibers and a polyester amide matrix were produced with fiber mass fractions between 0 and 0.48. The hot-pressed plates, 1-mm thick, were incubated in a standard soil. The degradation kinetics was quantified by the measurement of CO2 production. Furthermore, after termination of experiment, the carbon balance was uncovered. The results were fitted to an exponential law taking into account the degradation of fibers. The increased amount of pores realized by high fiber contents induces pronounced degradation. The degradation is fully characterized by the time constant τ, which is correlated to the fiber mass fraction. The model allows to predict the degradation kinetics of composites with a few well-defined experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011574021257
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  • 6
    Electronic Resource
    Electronic Resource
    A Sensitive Electrochemical Impedance Spectroscopy Method for Detection of Polyimide Degradation by Microorganisms (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 167-174 
    Details
    ISSN: 1572-8900
    Keywords: Polyimides ; electronic insulation ; biodegradation ; biodeterioration ; fungi ; electrochemical impedance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An electrochemical impedance spectroscopy (EIS) technique was evaluated for monitoring microbial degradation of electronic packaging polyimides. The microbial inoculum was a mixed culture of fungi isolated previously from deteriorated polyimides. The active fungal consortium comprised Aspergillus versicolor, Cladosporium cladosporioides, and a Chaetomium species. After inoculation, fungal growth on the polyimides resulted in distinctive EIS spectra indicative of polymer insulation failure, which directly related to polymer integrity. Degradation appeared to occur in a number of steps and two distinctive stages in the decline of film resistance were observed in the inoculated EIS cells within the 2 and 10 weeks after inoculation. The early stage of resistance decrease may be related to the ingress of water molecules and ionic species into the polymeric materials, whereas the second stage probably resulted from partial degradation of the polymers by fungal growth on the polymer film. The relationship between changes of impedance spectra and microbial degradation of the polymer was further supported by scanning electron microscopy (SEM) observations of fungi growing on the surface of the inoculated polyimides. Our data indicate that the EIS can be used in detection of early degradation of resistant polymers and polyimides that are susceptible to biodeterioration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015293626335
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  • 7
    Electronic Resource
    Electronic Resource
    Extruded Cornstarch-Glycerol-Polyvinyl Alcohol Blends: Mechanical Properties, Morphology, and Biodegradability (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 205-211 
    Details
    ISSN: 1572-8900
    Keywords: Extruded ; polyvinyl alcohol ; starch ; glycerol ; biodegradation ; films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Elongation properties of extruded cornstarch were improved by blending with glycerol. Further blending of starch-glycerol with polyvinyl alcohol (PVOH) resulted in significant improvements in both tensile strength (TS) and elongation at break. Samples of starch-glycerol without PVOH equilibrated at 50% relative humidity had a TS of 1.8 MPa and elongation of 113%, whereas those containing PVOH had a TS and elongation of 4 MPa and 150%, respectively. Dynamic mechanical analysis (DMA) of starch-glycerol-PVOH blends showed that decreases in glass transition temperatures (T g values) were proportional to glycerol content. Scanning electron microscopy (SEM) of fractured surfaces revealed numerous cracks in starch-glycerol (80:20) samples. Cracks were absent in starch-glycerol (70:30) samples. In both blends, many starch granules were exposed at the surface. No exposed starch granules were visible in blends with added PVOH. Starch-glycerol samples incubated in compost lost up to 70% of their dry weight within 22 days. Addition of PVOH lowered both the rate and extent of biodegradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015201928153
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  • 8
    Electronic Resource
    Electronic Resource
    Biodegradation and conversion of alkanes and crude oil by a marine Rhodococcus (2000)
    Springer
    Biodegradation 11 (2000), S. 289-294 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; cellular fatty acids ; crude oil ; end products ; hydrocarbons ; rhodococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A hydrocarbon degrader isolated from a chronically oil-polluted marine site was identified as Rhodococcus sp. on the basis of morphology, fatty acid methyl ester pattern, cell wall analysis, biochemical tests and G + C content of DNA. It degraded upto 50% of the aliphatic fraction of Assam crude oil, in seawater supplemented with 35 mM nitrogen as urea and 0.1 mM phosphorus as dipotassium hydrogen orthophosphate, after 72 h at 30 ° and 150 revolutions per minute. The relative percentage of intracellular fatty acid was higher in hydrocarbon-grown cells compared to fructose-grown cells. The fatty acids C16 , C1616 :1 C18 and C18 : 1 were constitutively present regardless of the growth substrate. In addition to these constitutive acids, other intracellular fatty acids varied in correlation to the hydrocarbon chain length supplied as a substrate. When grown on odd carbon number alkanes, the isolate released only monocarboxylic acids into the growth medium. On even carbon number alkanes only dicarboxylic acids were produced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011185806974
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  • 9
    Electronic Resource
    Electronic Resource
    Degradation of microbial polyester poly(3-hydroxybutyrate) in environmental samples and in culture (2000)
    Springer
    Biodegradation 11 (2000), S. 323-329 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; microbial polyester ; poly(3-hydroxybutyrate) ; poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Poly(3-hydroxybutyrate) [P(3HB)] test-pieces prepared from the polymer produced by Azotobacter chroococcum were degraded in natural environments like soil, water, compost and sewage sludge incubated under laboratory conditions. Degradation in terms of % weight loss of the polymer was maximum (45%) in sewage sludge after 200 days of incubation at 30°C. The P(3HB)-degrading bacterial cultures (36) isolated from degraded test-pieces showed different degrees of degradation in polymer overlayer method. The extent of P(3HB) degradation increases up to 12 days of incubation and was maximum at 30°C for majority of the cultures. For most efficient cultures the optimum concentration of P(3HB) for degradation was 0.3% (w/v). Supplementation of soluble carbon sources like glucose, fructose and arabinose reduced the degradation while it was almost unaffected with lactose. Though the cultures degraded P(3HB) significantly, they were comparatively less efficient in utilizing copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate [P(3HB-co-3HV)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011162624704
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  • 10
    Electronic Resource
    Electronic Resource
    Application of biofiltration to the degradation of hydrogen sulfide in gas effluents (2000)
    Springer
    Biodegradation 11 (2000), S. 423-427 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; biofiltration ; hydrogen sulfide ; malodorous compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A laboratory scale bioreactor has been designed and set up in order to degrade hydrogen sulfide from an air stream. The reactor is a vertical column of 7 litre capacity and 1 meter in height. It is divided into three modules and each module is filled with pellets of agricultural residues as packing bed material. The gas stream fed into the reactor through the upper inlet consists of a mixture of hydrogen sulfide and humidified air. The hydrogen sulfide content in the inlet gas stream was increased in stages until the degradation efficiency was below 90%. The parameters to be controlled in order to reach continuous and stable operation were temperature, moisture content and the percentage of the compound to be degraded at the inlet and outlet gas streams (removal or elimination efficiency). When the H2S mass loading rate was between 10 and 40 g m-3h-1, the removal efficiency was greater than 90%. The support material had a good physical performance throughout operation time, which is evidence that this material is suitable for biofiltration purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011615906278
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  • 11
    Electronic Resource
    Electronic Resource
    Viscosity properties of mineral paraffinic base oils as a key factor in their primary biodegradability (2000)
    Springer
    Biodegradation 11 (2000), S. 365-369 
    Details
    ISSN: 1572-9729
    Keywords: aromatic hydrocarbons ; biodegradation ; CEC L-33-A-93 test ; lubricants ; mineral base oils ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The primary biodegradability of two types of paraffinic base oils (solvent and catalytically dewaxed oils) and their blends was evaluated using the CEC L-33-A-93 test. The biodegradability values varied between 10% and 75%. Base oil mixtures displayed varying contents in aromatic and polar compounds and a wide range of kinematic viscosity (KV) values, from roughly 10 to 600 cSt (at 40°C), while their viscosity indices were almost constant (90-100). The biodegradability of oils was closely related to their content in polycyclic aromatic hydrocarbons and was also decreasing with kinematic viscosity. For the two types of base oils, a linear relationship could be set between the biodegradation percentages and the logarithms of KV values. These results show that, beside overall chemical features such as the contents in aromatic compounds, KV may be a prominent parameter for assessing the primary biodegradability of mineral base oils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011672016757
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  • 12
    Electronic Resource
    Electronic Resource
    Anaerobic utilization of essential oils bydenitrifying bacteria (2000)
    Springer
    Biodegradation 11 (2000), S. 55-63 
    Details
    ISSN: 1572-9729
    Keywords: Alcaligenes defragrans ; biodegradation ; essential oil ; monoterpenes ; nitrate reduction ; plant ; volatile organic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant volatile organic compounds are a major carbonsource in nature. We studied the degradability ofthese substances by anaerobic microorganisms inenrichment cultures with representative essential oilsas organic substrates and nitrate as electronacceptor. Lemon and pine needle oil supportedmicrobial growth in the presence of pure oil, whereasparsley seed, camphor, sage, fennel, and mint oilsupported growth only when the essential oils weredissolved in an overlying phase of2,2,4,4,6,8,8-heptamethylnonane. Thyme oil did notsupport denitrification. Analyses of the microbiallydegraded oils revealed the disappearance ofmonoterpenes, of several monoterpenoids, and ofmethoxy-propenyl-benzenes, including apiole andmyristicin. Most-probable-number determinations fordenitrifying communities in sewage sludge and forestsoil yielded 106 to 107monoterpene-utilizing cells ml-1, representing0.7 to 100% of the total cultivablenitrate-reducing microorganisms. The utilization ofessential oils together with the common occurrence ofthis metabolic trait are indications for anenvironmentally important, but currently unexploredanaerobic turnover of plant volatile organic compoundsin soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026552724696
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  • 13
    Electronic Resource
    Electronic Resource
    Enhancement of hydrocarbon wastebiodegradation by addition of a biosurfactantfrom Bacillus subtilis O9 (2000)
    Springer
    Biodegradation 11 (2000), S. 65-71 
    Details
    ISSN: 1572-9729
    Keywords: Availability ; Bacillus ; biodegradation ; biosurfactant ; hydrocarbon ; surfactin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A non-sterile biosurfactant preparation (surfactin)was obtained from a 24-h culture of Bacillussubtilis O9 grown on sucrose and used to study itseffect on the biodegradation of hydrocarbon wastes byan indigenous microbial community at theErlenmeyer-flask scale. Crude biosurfactant was addedto the cultures to obtain concentrations above andbelow the critical micelle concentration (CMC). Lowerconcentration affected neither biodegradation normicrobial growth. Higher concentration gave highercell concentrations. Biodegradation of aliphatichydrocarbons increased from 20.9 to 35.5% and in thecase of aromatic hydrocarbons from nil to 41%,compared to the culture without biosurfactant. Theenhancement effect of biosurfactant addition was morenoticeable in the case of long chain alkanes. Pristaneand phytane isoprenoids were degraded to the sameextent as n-C17 and n-C18 alkanes and, consequently,no decrease in the ratios n-C17/pri and n-C18/phy wasobserved. Rapid production of surfactin crudepreparation could make it practical for bioremediationof ship bilge wastes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026513312169
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  • 14
    Electronic Resource
    Electronic Resource
    Enhanced anaerobic bioremediation of groundwater contaminated by fuel hydrocarbons at Seal Beach, California (2000)
    Springer
    Biodegradation 11 (2000), S. 159-170 
    Details
    ISSN: 1572-9729
    Keywords: anaerobic ; biodegradation ; BTEX ; fuel ; hydrocarbons ; Seal Beach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Enhanced anaerobic biodegradation of groundwater contaminated by fuel hydrocarbons has been evaluated at a field experiment conducted at the Naval Weapons Station, Seal Beach, California. This experiment included the establishment of three different remediation zones in situ: one zone was augmented with sulfate, one was augmented with sulfate and nitrate, and the third was unaugmented. This enables a comparison of hydrocarbon biodegradation under sulfate-reducing, sequential denitrifying/sulfate-reducing, and methanogenic conditions, respectively. In general, the results from the field experiment are: (1) Certain fuel hydrocarbons were removed preferentially over others, but the order of preference is dependent upon the geochemical conditions; and (2) In the zones that were augmented with sulfate and/or nitrate, the added electron acceptors were consumed quickly, indicating that enhancement via electron acceptor injection accelerates the biodegradation process. More specifically, in the sulfate-reducing zone, sulfate was utilized with an apparent first-order rate coefficient of approximately 0.1 day-1. In the combined denitrifying/sulfate-reducing zone, nitrate was utilized preferentially over sulfate, with an apparent first-order rate coefficient of 0.1–0.6 day-1. However, the data suggest that slow sulfate utilization does occur in the presence of nitrate, i.e., the two processes are not strictly sequential. With regard to the aromatic BTEX hydrocarbons, toluene was preferentially removed under intrinsic conditions; biodegradation of benzene was slow if it occurred at all; augmentation with sulfate preferentially stimulated biodegradation of o-xylene; and ethylbenzene appeared recalcitrant under sulfate-reducing conditions but readily degradable under denitrifying conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011167709913
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  • 15
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    Aerobic MTBE biodegradation: an examination of past studies, current challenges and future research directions (2000)
    Springer
    Biodegradation 11 (2000), S. 171-185 
    Details
    ISSN: 1572-9729
    Keywords: aerobic ; bioremediation ; biodegradation ; gasoline ; MTBE ; TBA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the current practice of amending gasoline with up to 15% by volume MTBE, the contamination of groundwater by MTBE has become widespread. As a result, the bioremediation of MTBE-impacted aquifers has become an active area of research. A review of the current literature on the aerobic biodegradation of MTBE reveals that a number of cultures from diverse environments can either partially degrade or completely mineralize MTBE. MTBE is either utilized as a sole carbon and energy source or is degraded cometabolically by cultures grown on alkanes. Reported degradation rates range from 0.3 to 50 mg MTBE/g cells/h while growth rates (0.01–0.05 g MTBE/g cells/d) and cellular yields (0.1–0.2 g cells/g MTBE) are generally low. Studies on the mechanisms of MTBE degradation indicate that a monooxygenase enzyme cleaves the ether bond yielding tert-butyl alcohol (TBA) and formaldehyde as the dominant detectable intermediates. TBA is further degraded to 2-methyl-2-hydroxy-1-propanol, 2-hydroxyisobutyric acid, 2-propanol, acetone, hydroxyacteone and eventually, carbon dioxide. The majority of these intermediates are also common to mammalian MTBE metabolism. Laboratory studies on the degradation of MTBE in the presence of gasoline aromatics reveal that while degradation rates of other gasoline components are generally not inhibited by MTBE, MTBE degradation could be inhibited in the presence of more easily biodegradable compounds. Controlled field studies are clearly needed to elucidate MTBE degradation potential in co-contaminant plumes. Based on the reviewed studies, it is likely that a bioremediation strategy involving direct metabolism, cometabolism, bioaugmentation, or some combination thereof, could be applied as a feasible and cost-effective treatment method for MTBE contamination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011113320414
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  • 16
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    Mineralization of 1,4-dioxane in the presence of a structural analog (2000)
    Springer
    Biodegradation 11 (2000), S. 239-246 
    Details
    ISSN: 1572-9729
    Keywords: 1,4-Dioxane ; biodegradation ; cometabolism ; ethers ; tetrahydrofuran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A mixed culture with the ability to aerobically biodegrade 1,4-dioxane in the presence of tetrahydrofuran (THF) was enriched from a 1,4-dioxane contaminated aquifer. This consortium contained 3–4 morphologically different types of colonies and was grown in mineral salts media. Biodegradation of 1,4- dioxane began when THF concentrations in batch experiments became relatively low. No biodegradation of 1,4-dioxane was observed in the absence of THF and the measured cell yield was similar during degradation of 1,4-dioxane with THF or with THF alone. However, when the consortium was grown in the presence of 14C-1,4-dioxane plus THF, 2.1% of the radiolabeled 1,4-dioxane was present in the particulate fraction. The majority of the 14C (78.1%) was recovered as 14CO2, while 5.8% remained in the liquid fraction. This activity is interesting since the non-growth substrate is mineralized, yet only minimally assimilated into biomass. Using THF as the growth substrate, 1,3-dioxane, methyl t-butyl ether, ethyl t-butyl ether and t-amyl methyl ether.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011156924700
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  • 17
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    Distribution in the environment of degradative capacitiesfor gasoline attenuation (2000)
    Springer
    Biodegradation 11 (2000), S. 29-35 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; gasoline ; hydrocarbon ; intrinsic capacities ; natural attenuation ; soil pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A methodology allowing the detailed assessment ofthe capacities of microflorae to degrade gasoline inaerobic conditions has been developed. It consisted inthe determination of the degradation of a gasolinemodel mixture in liquid cultures in optimalconditions. The gasoline model mixture contained 23representative hydrocarbons of gasoline (GM23). Thekinetics and extent of biodegradation were evaluatedby continuous overall monitoring of CO2production and final chromatographic analysis (usuallyafter about 30 days) of the consumption of eachhydrocarbon. The methodology was used with soil andwater samples from polluted and non polluted sites.The experimentation aimed at assessing thedistribution of the degradative capacities in theenvironment and the prospects for natural attenuationof gasoline. Nine microflorae were tested. The intrinsicbiodegradability (existence of mechanisms ofbiodegradation) appeared total for GM23 as shown bythe results obtained with several microflorae. Thedegradative capacities of microflorae from nonpolluted samples were high (total degradation rates atleast 85%). Incomplete degradation was observedessentially for trimethylalkanes(2,2,4-trimethylpentane and 2,3,4-trimethylpentane)and for cyclohexane. In several cases, samples frompolluted sites exhibited more extensive degradativecapacities, with total degradation of all hydrocarbonsbeing observed for three out of the six samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026594717754
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    Biodegradation of Chitosan-Gellan and Poly(L-lysine)-Gellan Polyion Complex Fibers by Pure Cultures of Soil Filamentous Fungi (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 59-66 
    Details
    ISSN: 1572-8900
    Keywords: Polyion complex fibers ; biodegradation ; soil filamentous fungi, chitosan ; poly(L-lysine) ; gellan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The degradation of two kinds of polyion complex (PIC) fibers, chitosan-gellan (CGF), and poly(L-lysine)-gellan (LGF) fibers, by seven species of soil filamentous fungi has been investigated. All of the pure-line soil filamentous fungi, Aspergillus oryzae, Penicillium caseicolum, P. citrinum, Mucor sp., Rhizopus sp., Curvularia sp., and Cladosporium sp. grew on the two fiber materials. Microscopic observation of the biodegradation processes revealed that P. caseicolum on the CGF and LGF grew, along with the accompanying collapse of the fiber matrices. In the biochemical oxygen-demand (BOD) test, the biodegradation of the LGF by P. caseicolum and Curvularia sp. exceeded 97% carbon dioxide generation and the biodegradation of the CGF by A. oryzae was 59%. These results might offer some clues to the applications of the PIC fibers as environmentally biodegradable materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011517903510
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    Biodegradation of Recalictrant Components of Organic Mixtures (2000)
    Springer
    Water, air & soil pollution 123 (2000), S. 133-146 
    Details
    ISSN: 1573-2932
    Keywords: recalcitrat organics ; biodegradation ; biofiltration ; methyl tert-butyl ether ; dichloromethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Biodegradation of two recalcitrant compounds, dichloromethane and methyl tert-butyl ether was investigated individually and in combination with toluene and benzene. A vapor phase biofilter operating at an air flux of 1 m3/m2·min and an empty bed residence time of 1 minute was used as the reaction system. Inlet recalcitrant contaminant concentrations were typically 35 ppm on a volume basis while the aromatic compound concentrations were varied from 8 ppm to 150 ppm. Dichloromethane removals were not impacted by the introduction of toluene. However, a rapid decrease in methyl tert-butyl ether removal resulted from the initial introduction of toluene. Complete removal of both methyl tert-butyl ether and toluene was achieved within a week of operation.
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    URL: http://dx.doi.org/10.1023/A:1005226229320
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    Effect of Crystalline and Amorphous Structures on Biodegradability of Poly(Tetramethylene Succinate) (1999)
    Springer
    Journal of polymers and the environment 7 (1999), S. 19-26 
    Details
    ISSN: 1572-8900
    Keywords: Poly(tetramethylene succinate) ; amorphous and crystalline orientation ; biodegradation ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of orientation in the amorphous and crystalline regions on the biodegradability of PTMS [poly(tetramethylene succinate)] was studied using the amorphous orientation function, birefringence, and crystallinity. The crystalline and amorphous intrinsic lateral sonic moduli, E t,c 0 and E t,am 0 , were 2.61 × 103 and 0.41 × 103 MPa, respectively. Using the data on birefringence, crystalline and amorphous orientation function (f ∈ and f am), crystallinity, and sonic modulus of the oriented PTMS fibers, the intrinsic birefringence of the crystalline (Δ c 0 ) and amorphous (Δ am 0 ) regions were evaluated to be 0.0561 and 0.0634, respectively. The biodegradabilities of oriented PTMS films were reduced as the elongation increased, i.e., the amorphous orientation increased. At low elongation (100 and 150%), however, biodegradabilities remained unchanged when the degradation test was performed in activated sludge, which was attributed to the amorphous orientation occurring even at 100% elongation, though the amorphous orientation direction was perpendicular to the fiber axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021838017958
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    Kinetics of Aerobic Polymer Degradation in Soil by Means of the ASTM D 5988-96 Standard Method (1999)
    Springer
    Journal of polymers and the environment 7 (1999), S. 109-116 
    Details
    ISSN: 1572-8900
    Keywords: Kinetics ; aerobic ; biodegradation ; poly-3-hydroxybutyrate ; poly-ɛ-caprolactone ; ASTM D 5988-96
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The standard test method ASTM D 5988-96 for determining the degree and rate of aerobic biodegradation of plastic materials in contact with soil was applied to poly(3-hydroxybutyrate) and poly(ɛ-caprolactone). The method proved to be reliable and supplied reproducible measurements of CO2 production, provided potassium (instead of barium) hydroxide was used as a trapping solution. The trends of CO2 evolution, as a function of time, observed for the degradation of polymer powders in soil are similar to those predicted by simple first order kinetics in solution. The experimental data are described by a Michaelis–Menten type model, which accounts for the heterogeneity of the polymer-soil system. The kinetic equation deduced predicts the degradation rate to the proportional to the exposed polymer surface area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021864402395
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    Thermodynamic and Diffusion Properties of Biodegradable Systems Based on Starch and Cellulose Derivatives (1999)
    Springer
    Journal of polymers and the environment 7 (1999), S. 35-40 
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    ISSN: 1572-8900
    Keywords: Starch ; starch blends ; sorption ; diffusion ; biodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The interval sorption and diffusion of water vapor were studied for two systems: methylcellulose (MC)/starch and carboxymethylcellulose (CMC)/starch. The diffusion coefficient of water vapor and the Gibbs free energy of swelling of these blends in water were estimated. The Gibbs free energy of mixing starch with the cellulose derivatives was determined using the thermodynamic cycle. CMC/starch was shown to be more compatible than MC/starch. Biodegradation of these systems in the water–soil environment was measured and found to increase with the concentration of starch in its blends with cellulose derivatives.
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    URL: http://dx.doi.org/10.1023/A:1021842118866
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    Two-liquid-phase bioreactors for enhanced degradation of hydrophobic/toxic compounds (1999)
    Springer
    Biodegradation 10 (1999), S. 219-233 
    Details
    ISSN: 1572-9729
    Keywords: bioavailability ; biodegradation ; bioreactor ; biotreatment ; NAPL ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two-liquid-phase culture systems involve the addition of a water-immiscible, biocompatible and non-biodegradable solvent to enhance a biocatalytic process. Two-liquid-phase bioreactors have been used since the mid-seventies for the microbial and enzymatic bioconversion of hydrophobic/toxic substrates into products of commercial interest. The increasing popularity of bioremediation technologies suggests a new area of application for this type of bioreactor. The toxicity and the limited bioavailability of many pollutants are important obstacles that must first be overcome in order to improve biodegradation processes. Two-liquid-phase bioreactors have the potential to resolve both limitations of biotreatment technologies by the enhancement of the mass-transfer rate of compounds with low bioavailability, and by the controlled delivery of apolar toxic compounds. This technology can also be useful in accelerating the enrichment of microorganisms degrading problematic pollutants. In this paper, we discuss the application of two-liquid-phase bioreactors to enhance the biodegradation of toxic/poorly bioavailable contaminants. Important microbial mechanisms involved in this type of system are described. Uptake of the substrates can be achieved by microorganisms freely dispersed in the aqueous phase and/or bound at the interface between the aqueous and the immiscible phases. Production of surface-active compounds and adhesion abilities are microbial features involved in the process. General guidelines for the design of two-liquid-phase bioreactors for biodegradation purposes are presented. Solvent selection should be established on specific criteria, which depend on the characteristics of target compound(s) and the microorganism(s) implicated in the biodegradation process. The central importance of maximizing the interfacial surface area is highlighted. The potential of this approach as an alternative to current biotreatment technologies is also discussed.
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    URL: http://dx.doi.org/10.1023/A:1008311430525
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    Modelling the growth of a methanotrophic biofilm: Estimation of parameters and variability (1999)
    Springer
    Biodegradation 10 (1999), S. 177-191 
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    ISSN: 1572-9729
    Keywords: AQUASIM ; biodegradation ; biofilm ; growth ; kinetics ; methane ; modelling ; nitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This article discusses the growth of methanotrophic biofilms. Several independent biofilm growths scenarios involving different inocula were examined. Biofilm growth, substrate removal and product formation were monitored throughout the experiments. Based on the oxygen consumption it was concluded that heterotrophs and nitrifiers co-existed with methanotrophs in the biofilm. Heterotrophic biomass grew on soluble polymers formed by the hydrolysis of dead biomass entrapped in the biofilm. Nitrifier populations developed because of the presence of ammonia in the mineral medium. Based on these experimental results, the computer program AQUASIM was used to develop a biological model involving methanotrophs, heterotrophs and nitrifiers. The modelling of six independent growth experiments showed that stoichiometric and kinetic parameters were within the same order of magnitude. Parameter estimation yielded an average maximum growth rate for methanotrophs, μm, of 1.5 ± 0.5 d−1, at 20 °C, a decay rate, bm, of 0.24 ± 0.1 d−1, a half saturation constant, $${\text{K}}_{{\text{S(CH}}_{\text{4}} {\text{)}}} $$ , of 0.06 ± 0.05 mg CH4/L, and a yield coefficient, $$Y_{CH_4 } $$ , of 0.57 ±: 0.04 g X/g CH4. In addition, a sensitivity analysis was performed on this model. It indicated that the most influential parameters were those related to the biofilm (i.e. density; solid-volume fraction; thickness). This suggests that in order to improve the model, further research regarding the biofilm structure and composition is needed.
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    URL: http://dx.doi.org/10.1023/A:1008317906069
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    Anaerobic biodegradation of BTEX and gasoline in various aquatic sediments (1999)
    Springer
    Biodegradation 10 (1999), S. 15-25 
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    ISSN: 1572-9729
    Keywords: anaerobic ; biodegradation ; BTEX ; gasoline ; hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined the extent of biodegradation of benzene, toluene, ethylbenzene and the three isomers of xylene (BTEX) as a mixture and from gasoline in four different sediments: the New York/New Jersey Harbor estuary (polluted); Tuckerton, N.J. (pristine); Onondaga Lake, N.Y. (polluted) and Blue Mtn. Lake, N.Y. (pristine). Enrichment cultures were established with each sediment using denitrifying, sulfidogenic, methanogenic and iron reducing media, as well as site water. BTEX loss, as measured by GC-FID, was extensive in the sediments which had a long history of pollution, with all compounds being utilized within 21–91 days in the most active cultures, and was very slight or non-existent in the pristine sediments. Also, the pattern of loss was different under the various reducing conditions within each sediment and between sediments. For example benzene loss was only observed in sulfidogenic cultures from the NY/NJ Harbor sediments while toluene was degraded under all redox conditions. The loss of BTEX was correlated to the reduction of the various electron acceptors. In cultures amended with gasoline the degradation was much slower and incomplete. These results show that the fate of the different BTEX components in anoxic sediments is dependent on the prevailing redox conditions as well as on the characteristics and pollution history of the sediment.
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    URL: http://dx.doi.org/10.1023/A:1008303729431
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    Effect of nitrogen and phosphorus addition on phenanthrene biodegradation in four soils (1999)
    Springer
    Biodegradation 10 (1999), S. 43-50 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; nitrogen ; nutrients ; phenanthrene ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phenanthrene mineralization rates were found to vary widely among four soils; differences in soil nutrient levels was one hypothesis to explain this variation. To test this hypothesis, phenanthrene mineralization rates were measured in these soils with, and without, added nitrogen and phosphorus. Mineralization rates either remained unchanged or were depressed by the addition of nitrogen and phosphorus. Phenanthrene degradation rates remained unchanged in the soil which had the highest indigenous levels of nitrogen and phosphorus and which showed the largest increase in phosphorus levels after nutrients were added. The soils in which degradation rates were depressed had lower initial phosphorus concentrations and showed much smaller or no measurable increase in phosphorus levels after nutrients were added to the soils. To understand the response of phenanthrene degradation rates to added nitrogen and phosphorus, it may be necessary to consider the bioavailability of added nutrients and nutrient induced changes in microbial metabolism and ecology.
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    URL: http://dx.doi.org/10.1023/A:1008359606545
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    Biofilter performance and characterization of a biocatalyst degrading alkylbenzene gases (1999)
    Springer
    Biodegradation 10 (1999), S. 169-176 
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    ISSN: 1572-9729
    Keywords: biodegradation ; biofiltration ; bioremediation ; extremophile ; VOC ; waste gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A biofilter treating alkylbenzene vapors was characterized for its optimal running conditions and kinetic parame-ters. Kinetics of the continuous biofilter were compared to batch kinetic data obtained with biofilm samples as well as with defined microbial consortia and with pure culture isolates from the biofilter. Both bacteria and fungi were present in the bioreactor. Five strains were isolated. Two bacteria, Bacillus and Pseudomonas, were shown to be dominant, as well as a Trichosporon strain which could, however, hardly grow on alkylbenzenes in pure culture. The remaining two strains were most often overgrown by the other three organisms in liquid phase batch cultures μ max, KS, KI values and biodegradation rates were calculated and compared for the difterent mixed and pure cultures. Since filter bed acidification was observed during biofiltration studies reaching a pH of about 4, experiments were also undertaken to study the influence of pH on performance of the different cultures. Biodegradation and growth were possible in all cases, over the pH range 3.5–7.0 at appreciable rates, both with mixed cultures and with pure bacterial cultures. Under certain conditions, microbial activity was even observed in the presence of alkylbenzenes down to pH 2.5 with mixed cultures, which is quite unusual and explains the ability of the present biocatalyst to remove alkylbenzenes with high efficiency in biofilters under acidic conditions.
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    URL: http://dx.doi.org/10.1023/A:1008301415192
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    Biodegradation of xylene and butyl acetate using an aqueous-silicon oil two-phase system (1999)
    Springer
    Biodegradation 10 (1999), S. 193-200 
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    ISSN: 1572-9729
    Keywords: biodegradation ; butyl acetate ; selection of microorganisms ; silicon oil ; two-phase aqueous-organic system ; xylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A stable microbial population, consisting of seven bacterial strains and three yeast strains, was selected in batch cultures on a mixture of ortho and meta-xylene and butyl acetate as the sole source of carbon and energy. This population can completely degrade up to 10 g/L of a mixture of these xenobiotics (70% xylene and 30% butyl acetate wt/wt) in a two-phase aqueous-silicone oil system (70%/30% vol/vol) within 96 h, while for the usual one-phase system very low growth degradation rates were observed. Further organic solvents were tested and finally, silicon oil was selected as the best organic phase for such a two-phase system. With periodical pH adjustments to 6.0 in fed-batch mode, the culture showed a global degradation rate of 63 mg L-1 h-1.
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    URL: http://dx.doi.org/10.1023/A:1008328318442
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    Growth inhibition of biomass adapted to the degradation of toluene and xylenes in mixture in a batch reactor with substrates supplied by pulses (1999)
    Springer
    Biodegradation 10 (1999), S. 245-250 
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    ISSN: 1572-9729
    Keywords: biodegradation ; growth inhibition ; metabolites ; toluene ; xylenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A biomass adapted to degrade toluene and xylenes in mixture was grown in a batch reactor with substrates supplied by pulses. The inhibition of biomass growth in the course of substrate degradation was investigated. The maximal biomass concentration of 7 g l−1 was obtained using 150 μl of toluene and 15 μl of a mixture of xylenes in one litre of liquid medium, and the maximal biomass productivity and yield were 53 mg l−1 h−1 and 0.32 gDW g s −1 , respectively. Higher quantities of substrate added by pulses, that is 200 μl of toluene with 20 μl of xylenes and 300 μl of toluene with 30 μl of xylenes, caused an accumulation of metabolites. These higher quantities of substrates caused inhibition of microbial growth. Among the metabolites produced, 4-methyl catechol was found in large quantities in the culture medium and in the cells.
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    URL: http://dx.doi.org/10.1023/A:1008363422254
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    A comparison of the ability of forest and agricultural soils to mineralize chlorinated aromatic compounds (1999)
    Springer
    Biodegradation 10 (1999), S. 235-244 
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    ISSN: 1572-9729
    Keywords: Atrazine ; biodegradation ; chlorophenolics ; 2,4-D ; PCP ; pristine soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soils were sampled from two agricultural fields, two relatively pristine forests, and one suburban forest in Ontario, Canada. The ability of these soils to mineralize 2,4-dichlorophenoxyacetate, 3-chlorobenzoate, 4-chlorophenol, 2,4-dichlorophenol, pentachlorophenol, and atrazine was determined using 14C-labeled substrates. Direct preexposure was necessary before atrazine mineralization could be detected; however, it was not necessary for degradation of any of the other chemicals. 2,4-dichlorophenoxyacetate and pentachlorophenol mineralization was much higher in the agricultural soils relative to the pristine forest soils, but 3-chlorobenzoate and 2,4-dichlorophenol mineralization rates showed the opposite trend. Mineralization of 4-chlorophenol was about equivalent in all soils. Suburban forests soils were indistinguishable from agricultural soils with respect to their degradation of 2,4-dichlorophenoxyacetate and chlorobenzoate. Additionally, they were better able than any of the soils to withstand the toxic effects of pentachlorophenol. Pentachlorophenol mineralization was highly variable in the pristine forest soils, ranging from about 6 to 50%. Abiotic factors such as pH, soil type, and organic and moisture content did not account for these significant site differences. The selective forces responsible for these differences, and the possible differences in microbial populations are discussed.
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    Degradation of mono-chlorophenols by a mixed microbial community via a meta- cleavage pathway (1999)
    Springer
    Biodegradation 10 (1999), S. 353-362 
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    ISSN: 1572-9729
    Keywords: mixed microbial community ; mono-chlorophenol ; biodegradation ; 3-chlorocatechol ; 5-chloro-2-hydroxymuconic semialdehyde ; meta- cleavage pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A mixed microbial community, specially designed todegrade a wide range of substituted aromaticcompounds, was examined for its ability to degrademono-chlorophenols as sole carbon source in aerobicbatch cultures. The mixed culture degraded 2-, 3-, and4 -chlorophenol (1.56 mM) via a meta- cleavagepathway. During the degradation of 2- and3-chlorophenol by the mixed culture, 3-chlorocatecholproduction was observed. Further metabolism was toxicto cells as it led to inactivation of the catechol2,3-dioxygenase enzyme upon meta- cleavage of3-chlorocatechol resulting in incomplete degradation.Inactivation of the meta- cleavage enzyme led toan accumulation of brown coloured polymers, whichinterfered with the measurement of cell growth usingoptical denstiy. Degradation of 4-chlorophenol by themixed culture led to an accumulation of5-chloro-2-hydroxymuconic semialdehyde, themeta- cleavage product of 4-chlorocatechol. Theaccumulation of this compound did not interfere withthe measurement of cell growth using optical density.5-chloro-2-hydroxymuconic semialdehyde was furthermetabolized by the mixed culture with a stoichiometricrelease of chloride, indicating complete degradationof 4-chlorophenol by the mixed culture via ameta- cleavage pathway.
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    Potential for Enhancement of Biodegradation of Crude Oil in Louisiana Salt Marshes using Nutrient Amendments (1999)
    Springer
    Water, air & soil pollution 109 (1999), S. 343-355 
    Details
    ISSN: 1573-2932
    Keywords: biodegradation ; crude oil ; salt marshes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Salt marsh ecosystems in Louisiana are at high risk of an oil contamination event while remediation of these systems is mainly limited to intrinsic bioremediation due to the physical sensitivity of salt marshes. This study investigated both the intrinsic and nutrient enhanced rates of crude oil degradation both in microcosm and core studies. In addition, limiting elements, loading rates and optimum nitrogen forms (NH 4 + or NO 3 - ) were determined. Salt marshes have relatively low intrinsic degradation rates (0–3.9% day-1) of the alkane component (C11-C44) but high rates (8–16% day-1) of degradation of the polycyclic aromatic hydrocarbon (PAH) fraction (naphthalene, C1, and C2-Naphthalene and Phenanthrene, C1, and C2-Phenanthrene). Additions of nitrogen statistically enhanced degradation of many alkanes and total PAHs while naturally present phosphorous was found to be sufficient. Nitrogen was found to be most effective if applied as NH 4 + in the range of 100-500-N mg kg-1 of soil producing a pore water range of 100-670-N mg L-1. Core studies indicate that similar trends are observed when applying fertilizers to intact portions of salt marsh.
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    URL: http://dx.doi.org/10.1023/A:1005025809014
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    Comparisons of Geochemical Signatures of Biotransformation of Fuel Hydrocarbons in Groundwater (1999)
    Springer
    Environmental monitoring and assessment 59 (1999), S. 257-274 
    Details
    ISSN: 1573-2959
    Keywords: biodegradation ; groundwater geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Biotransformation processes play an active role in reducing the environmental impact of fuel hydrocarbon releases to groundwater. Because monitoring data at release locations are typically sparse, spatial variations in geochemical indicator parameters are often called upon as indirect evidence of biotransformation. These parameters include concentrations of electron acceptors (O2, NO3 -, SO〉 4 2- , reduced redox reaction by-products (Fe2+, Mn2+, CH4), as well as bicarbonate alkalinity, pH and Eh. However, background variability in a number of these parameters complicates the task of data interpretation, particularly in the case of small data sets. In this study, correlation analyses are applied to geochemical indicator data at six hydrocarbon groundwater contamination sites in California to identify which parameters are the most reliable indicators. The results of the analyses suggest that the most direct indicators of the local redox environment – Fe2+, Mn2+, CH4, Eh – yield the most consistent evidence of hydrocarbon biotransformation. Indicators which rely largely on mass balance – O2, NO 3 - , SO 4 2- , alkalinity – appear to be less reliable. These findings may provide guidance in both the collection and interpretation of groundwater monitoring data at hydrocarbon contamination sites.
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    URL: http://dx.doi.org/10.1023/A:1006113520693
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    Effects of Nitrogen and Phosphorus Supply on Hexadecane Biodegradation in Soil Systems (1999)
    Springer
    Water, air & soil pollution 111 (1999), S. 1-18 
    Details
    ISSN: 1573-2932
    Keywords: biodegradation ; hydrocarbon ; nitrogen ; nutrient ratios ; phosphorus ; soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The biodegradation of hexadecane (C as hexadecane-C) was assessed under 34 different external nitrogen (N supplied as NO3-N) and phosphorus (P supplied as PO4-3-P) supply conditions in order to determine how different nutrient formulations affected nutrient limitation conditions during degradation. CO2 production yields indicated that shifts in N and P supply levels resulted in variable biodegradation responses due to shifts in the limiting-nutrient (e.g., from N to P). For example, the estimated maximum fractional CO2 yield ratio was 0.24 (mg CO2-C produced mg-1 hexadecane-C) for P-limited nutrient formulations (P:hexadecane-C〈0.01), whereas the yield ratio was more than two times greater when the system was not P- limited. Similar effects were observed for N-limited (N:hexadecane- C〈0.15) versus non-N-limited formulations. The relative bioavailability of natural soil-N and soil-P also was examined. In the soil studied, background soil-N was 96.3% organic-N and was found to be largely nonbioavailable. In contrast, high CO2 yields were observed even when no external P was supplied. An iterative mathematical procedure indicated that the Olsen soil-P subfraction (inorganic soil-P plus soluble organic soil- P) best approximated bioavailable soil-P for this soil. Our results indicate that both N and P additions affect biodegradation yields, but that stoichiometrically inappropriate nutrient mixes produce suboptimal CO2 yields. We also found that the bioavailable fractions of soil-N and soil-P should be incorporated into estimating the most suitable nutrient formulations for a given contamination scenario.
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    URL: http://dx.doi.org/10.1023/A:1005091427942
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    Degradation of Poly(Ethylene Glycol)-Based Nonionic Surfactants by Different Bacterial Isolates from River Water (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 121-131 
    Details
    ISSN: 1572-8900
    Keywords: Nonionic surfactants ; biodegradation ; alkylphenol poly(ethoxylate)s ; alkyl poly(ethoxylate)s ; polyethylene glycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Different bacterial strains able to attack polyoxyethylene-type nonionic surfactants were isolated by enrichment procedure from the surface waters of the Arno River. Alkylphenol polyethoxylates and alkyl polyethoxylates, as well as polyethylene glycols, were degraded and assimilated by bacterial strains in axenic cultures. Degradative routes of polyethyleneoxide chains were investigated by matching each bacterial isolate with several types of nonionic surfactants and polyethers and by the identification of their degradation products isolated during aerobic digestion experiments. In accordance with previous reports, the first attack led to the shortening of the poly(oxyethylene) chains of the nonionic surfactants. It was found that the strains able to degrade PEG segments of nonionic surfactants possess enzymatic systems unable to degrade free PEGs, whereas those degrading the latter substrates cannot degrade PEG segments coupled to hydrophobic moieties.
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    URL: http://dx.doi.org/10.1023/A:1021813312506
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    Influence of Processing Additives on the Degradation of Melt-Pressed Films of Poly(ε-Caprolactone) and Poly(Lactic Acid) (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 209-221 
    Details
    ISSN: 1572-8900
    Keywords: Poly(ε-caprolactone ; poly(lactic acid) ; processing additives ; biodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Melt-pressed films of polycaprolactone (PCL) and poly(lactic acid) (PLA) with processing additives, CaCO3, SiO2, and erucamide, were subjected to pure fungal cultures Aspergillus fumigatus and Penicillium simplicissimum and to composting. The PCL films showed a rapid weight loss with a minor reduction in the molecular weight after 45 days in A. fumigatus. The addition of SiO2 to PCL increased the rate of (bio)erosion in A. fumigatus and in compost. The use of a slip additive, erucamide, was shown to modify the properties of the film surface without decreasing the rate of bio(erosion). Both the rate of weight loss and the rate of molecular weight reduction of PCL increased with decreasing film thickness. The addition of CaCO3 to PLA significantly reduced the thermal degradation during processing, but it also reduced the rate of the subsequent (bio)degradation in the pure fungal cultures. PLA without additives and PLA containing SiO2 exhibited the fastest (bio)degradation, followed by PLA with CaCO3. The degradation of the PLA films was initially governed by chemical hydrolysis, followed by an acceleration of the weight change and of the molecular weight reduction. PLA film subjected to composting exhibits a rapid decrease in molecular weight, which then remains unchanged during the measurement period, probably because of crystallization.
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    URL: http://dx.doi.org/10.1023/A:1021829816140
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    Evaluation of the Biodegradation of Starch and Cellulose Under Controlled Composting Conditions (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 197-202 
    Details
    ISSN: 1572-8900
    Keywords: Starch ; cellulose ; biodegradation ; ISO/DIS 14855:1997 ; ASTM D 5338-92 ; priming effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In order to verify the response of the controlled composting test method (i.e., the ISO/DIS 14855:1997, the ASTM D 5338-92, or the CEN counterpart) to starch at different concentrations, the maximum amount prescribed by the test method (100 g) and lower amounts (60 and 30 g), as if starch were a coingredient in a blend, were tested. After 44 days of incubation (at a constant temperature of 58°C) the biodegradation curves were in a plateau phase, displaying the following final values (referred to a nominal starch initial amount of 100 g): starch 100 g, 97.5%; starch 60 g, 63.7%; and starch 30 g, 32.5%. The data show a CO2 evolution roughly equal, in each case, to the theoretical maximum, indicating a complete starch mineralization. We cannot discern whether the deviations found at lower concentrations are caused by a priming effect. In any case, the extent of the deviations is not high and is acceptable in biodegradation studies. The average biodegradation of cellulose, obtained gathering four independent experiments with 11 biodegradation curves, turned out to be 96.8 ± 6.7% (SD) after 47 ± 1 days. The data indicate that the controlled composting is a reliable test method also for starch and cellulose and, consequently, for starch-based and cellulose-based materials.
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    URL: http://dx.doi.org/10.1023/A:1021825715232
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    Molecular Weight Changes and Polymeric Matrix Changes Correlated with the Formation of Degradation Products in Biodegraded Polyethylene (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 187-195 
    Details
    ISSN: 1572-8900
    Keywords: LDPE ; biodegradation ; molecular weight changes ; degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products. The samples were thermooxidized for 6 days at 100°C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in $$\overline M _n$$ from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.
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    URL: http://dx.doi.org/10.1023/A:1021873631162
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    Microbial degradation of polymeric coatings measured by electrochemical impedance spectroscopy (1998)
    Springer
    Biodegradation 9 (1998), S. 39-45 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; biodeterioration ; coatings ; electrochemical impedance spectroscopy ; fungi ; polyimides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper reports results of biodegradation studies of polyimide coatings exposed to a mixed fungal culture using electrochemical impedance spectroscopy (EIS). The fungal consortium was originally isolated from degraded polyimides and identified species include Aspergillus versicolor, Cladosporium cladosporioides, and a Chaetomium species. Actively growing fungi on polyimides yield distinctive EIS spectra through time, indicative of failure of the polymer integrity compared to the uninoculated controls. An initial decline in coating resistance was related to the partial ingress of water molecules and ionic species into the polymeric matrices. This was followed by further degradation of the polymers by activity of the fungi. The relationship between the changes in impedance spectra and microbial degradation of the coatings was further supported by scanning electron microscopy, showing extensive colonization of the polyimide surfaces by the fungi. Our data indicate that EIS can be a sensitive and informative technique for evaluating the biosusceptibility of polymers and coatings.
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    URL: http://dx.doi.org/10.1023/A:1008252301377
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    Biodegradation of crude oil by soil microorganisms in the tropic (1998)
    Springer
    Biodegradation 9 (1998), S. 83-90 
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    ISSN: 1572-9729
    Keywords: alkanes ; biodegradation ; Candida tropicalis ; crude oil ; gas chromatography ; petroleum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Five microorganisms, three bacteria and two yeasts, capable of degrading Tapis light crude oil were isolated from oil-contaminated soil in Bangkok, Thailand. Soil enrichment culture was done by inoculating the soil in mineral salt medium with 0.5% v/v Tapis crude oil as the sole carbon source. Crude oil biodegradation was measured by gas chromatography method. Five strains of pure microorganisms with petroleum degrading ability were isolated: three were bacteria and the other two were yeasts. Candida tropicalis strains 7Y and 15Y were identified as efficient oil degraders. Strain 15Y was more efficient, it was able to reduce 87.3% of the total petroleum or 99.6% of n-alkanes within the 7-day incubation period at room temperature of 25 ± 2 °C.
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    URL: http://dx.doi.org/10.1023/A:1008272303740
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    Biodegradation of N-Methylmorpholine-N-oxide (1998)
    Springer
    Biodegradation 9 (1998), S. 91-102 
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    ISSN: 1572-9729
    Keywords: activated sludge ; biodegradation ; biological degradation ; lyocell fibres ; N-methylmorpholine-N-oxide ; wastewater treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract N-Methylmorpholine-N-oxide (NMMO) is capable of dissolving cellulose without any further addition of chemicals. The solution can be used to produce cellulosic staple fibres by pressing it through spinning jets into an aqueous spinning bath. Because of results from conventional biodegradation tests using non-adapted activated sludge, the solvent is generally considered being persistent. The object of the described work was to show, whether and how activated sludge can be adapted to N-methylmorpholine-N-oxide and whether it is possible to purify NMMO-containing wastewaters in conventional wastewater treatment plants. The experiments showed that the sludge can be adapted within about 15–20 days. Adapted sludge can degrade the substance itself and its most important metabolites to concentrations below their detection levels and retain this ability even during limited periods without solvent being present in the wastewater. The main requirement for a successful adaptation is a high sludge age. The degradation takes place in several steps. First, NMMO is reduced to N-methylmorpholine. The next step is a demethylation of N-methylmorpholine to morpholine. This step is crucial for the adaptation process. Once morpholine has been formed, the adaptation proceeds very quickly until none of the substances in question can be detected any longer. So the next step must be the cleavage of the morpholine ring structure.
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    Isolation of highly performant sulfate reducers from sulfate-rich environments (1998)
    Springer
    Biodegradation 9 (1998), S. 285-292 
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    ISSN: 1572-9729
    Keywords: biodegradation ; gypsum ; hydrogen ; inhibition ; isolation ; sulfate-reducing bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eleven pure strains of sulfate-reducing bacteria have been isolated from lab-scale bioreactors or gypsum disposal sites, all featuring relatively high concentrations of sulfate, and from natural environments in order to produce sulfide from gypsum using hydrogen as energy source. The properties of the eleven strains have been investigated and compared to these of three collection strains i.e. Desulfovibrio desulfuricans and Dv. vulgaris and Desulfotomaculum orientis. Particular attention was paid to the volumetric and specific sulfide production rate and to the hydrogen sulfide inhibition level. By comparison to the three collection strains, a 75% higher production rate and a hydrogen sulfide inhibition level about twice as high i.e. 25.1 mM have been achieved with strains isolated from sulfate-rich environments. The strain selection, particularly from sulfate-rich environments, should be considered as an optimization factor for the sulfate reduction processes.
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    URL: http://dx.doi.org/10.1023/A:1008382102417
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    Microbial degradation of tannins – A current perspective (1998)
    Springer
    Biodegradation 9 (1998), S. 343-357 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; condensed tannins ; gallic acid ; hydrolysable tannins ; quercetin ; rumen ; tannase ; tannins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tannins are water-soluble polyphenolic compounds having wide prevalence in plants. Hydrolysable and condensed tannins are the two major classes of tannins. These compounds have a range of effects on various organisms – from toxic effects on animals to growth inhibition of microorganisms. Some microbes are, however, resistant to tannins, and have developed various mechanisms and pathways for tannin degradation in their natural milieu. The microbial degradation of condensed tannins is, however, less than hydrolysable tannins in both aerobic and anaerobic environments. A number of microbes have also been isolated from the gastrointestinal tract of animals, which have the ability to break tannin-protein complexes and degrade tannins, especially hydrolysable tannins. Tannase, a key enzyme in the degradation of hydrolysable tannins, is present in a diverse group of microorganisms, including rumen bacteria. This enzyme is being increasingly used in a number of processes. Presently, there is a need for increased understanding of the biodegradation of condensed tannins, particularly in ruminants.
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    Influence of selected physical parameters on the biodegradation of acrylamide by immobilized cells of Rhodococcus sp. (1998)
    Springer
    Biodegradation 9 (1998), S. 381-387 
    Details
    ISSN: 1572-9729
    Keywords: acrylamide ; amidase ; biodegradation ; biotransformation ; immobilized cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influences of concentration of acrylamide, pH, temperature, duration of storage of encapsulated cells and presence of different metals and chelators on the ability of immobilized cells of a Rhodococcus sp. to degrade acrylamide were evaluated. Immobilized cells (3 g) rapidly degraded 64 and 128 mM acrylamide in 3 and 5 h, espectively, whereas free cells took more than 24 h to degrade 64 mM acrylamide. An acrylamide concentration of 128 mM inhibited the growth of the free cells. Immobilized bacteria were slow to degrade acrylamide at 10 °C. Less than 60% of acrylamide was degraded in 4 h. However, 100% of the compound was degraded in less than 3 h at 28 °C and 45 °C. The optimum pH for the degradation of acrylamide by encapsulated cells was pH 7.0. Less than 10% of acrylamide was degraded at pH 6.0, while ca. 60% of acrylamide was degraded at pH 8.0 and 8.5. Copper and nickel inhibited the degradation, suggesting the presence of sulfhydryl (-SH) groups in the active sites of the acrylamide degrading amidase. Iron enhanced the rates of degradation and chelators (EDTA and 1,10 phenanthroline) reduced the rates of degradation suggesting the involvement of iron in its active site(s) of the acrylamide-degrading-amidase. Immobilized cells could be stored up to 10 days without any detectable loss of acrylamide-degrading activity.
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    Nuclear magnetic resonance in environmental engineering: Principles and applications (1998)
    Springer
    Biodegradation 9 (1998), S. 393-409 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; bioreactors ; NMR imaging ; NMR spectroscopy ; nutrient removal ; sludge ; solid waste
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper gives an introduction to nuclear magnetic resonance spectroscopy (NMR) and magnetic resonance imaging (MRI) in relation to applications in the field of environmental science and engineering. The underlying principles of high resolution solution and solid state NMR, relaxation time measurements and imaging are presented. Then, the use of NMR is illustrated and reviewed in studies of biodegradation and biotransformation of soluble and solid organic matter, removal of nutrients and xenobiotics, fate of heavy metal ions, and transport processes in bioreactor systems.
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    URL: http://dx.doi.org/10.1023/A:1008316031421
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    19F NMR study on the biodegradation of fluorophenols by various Rhodococcus species (1998)
    Springer
    Biodegradation 9 (1998), S. 475-486 
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    ISSN: 1572-9729
    Keywords: biodegradation ; fluorophenols ; 19 F NMR ; oxidative defluorination ; Rhodococcus species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Of all NMR observable isotopes 19F is the one perhaps most convenient for studies on biodegradation of environmental pollutants. The reasons underlying this potential of 19F NMR are discussed and illustrated on the basis of a study on the biodegradation of fluorophenols by four Rhodococcus strains. The results indicate marked differences between the biodegradation pathways of fluorophenols among the various Rhodococcus species. This holds not only for the level and nature of the fluorinated biodegradation pathway intermediates that accumulate, but also for the regioselectivity of the initial hydroxylation step. Several of the Rhodococcus species contain a phenol hydroxylase that catalyses the oxidative defluorination of ortho-fluorinated di- and trifluorophenols. Furthermore, it is illustrated how the 19F NMR technique can be used as a tool in the process of identification of an accumulated unknown metabolite, in this case most likely 5-fluoromaleylacetate. Altogether, the 19F NMR technique proved valid to obtain detailed information on the microbial biodegradation pathways of fluorinated organics, but also to provide information on the specificity of enzymes generally considered unstable and, for this reason, not much studied so far.
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    Biodegradation of Polyaromatics Synthesized by Peroxidase-Catalyzed Free-Radical Polymerization (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 115-120 
    Details
    ISSN: 1572-8900
    Keywords: Polyaromatics ; free-radical polymerization ; biodegradation ; peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polymers formed from peroxidase-based free-radical polymerization reactions were characterized for rates of mineralization against lignin and humic acid controls. Degradation studies were carried out in soil systems over 202 days and cumulative net CO2 was determined. Whereas mineralization of the humic acid and alkali lignin controls totaled ca. 20% at the end of the test exposure, there was essentially no net mineralization of the hydrolytic lignin control. Mineralization of the test samples totaled 5% for poly(p-ethylphenol) and 11% for poly(m-cresol). At the same time, mineralization of the poly(p-phenyl phenol) totaled 64%. Conversely, the readily biodegradable polymers cellulose and PHB reached values of 91 to 97% in less than 60 days. Our data suggest that the mineralization kinetics of the enzymatically derived polyaromatics mimic those of the naturally occurring heteropolymers.
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    Synthesis, Characterization, and Hydrolytic Degradation of Copolymers of 2-Methylene-1,3-dioxepane with Ethylene and with Styrene (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 23-29 
    Details
    ISSN: 1572-8900
    Keywords: Polyethylene ; polystyrene ; biodegradation ; copolymerization ; hydrolytic degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract 2-Methylene-1,3-dioxepane (MDP) was copolymerized with ethylene (E) at a pressure of approximately 1000 psi and a temperature of approximately 70°C with AIBN as the free radical initiator. The copolymers obtained, poly(MDP-co-E), were characterized by elemental analysis, IR, 1H-NMR and 13C-NMR spectroscopy, DSC, and GPC. The copolymers contained 2–15 mol% ester units. MDP was also copolymerized with styrene (S) at 120°C with di-t-butyl peroxide as the initiator to prepare the copolymer, poly(MDP-co-S). The number-average molecular weights of both types of copolymers were in the range of 6000 to 11,000, and the weight-average molecular weights were in the range of 9000 to 17,000. The melting temperatures of poly(MDP-co-E) decreased with increasing ester unit content in the copolymer. For the MDP-S copolymers, the glass transition temperatures decreased with increasing ester unit content. Both poly(MDP-co-E) and poly(MDP-co-S) were degraded by methanolysis, and their molecular weights decreased by the expected amounts based on the ester unit content.
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    Biodegradation of Injection Molded Starch-Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) Blends in a Natural Compost Environment (1998)
    Springer
    Journal of polymers and the environment 6 (1998), S. 91-98 
    Details
    ISSN: 1572-8900
    Keywords: Starch ; PHBV ; PHA ; plastic ; blends ; biodegradation ; soil ; compost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Injection molded specimens were prepared by blending poly (hydroxybutyrate-co-valerate) (PHBV) with cornstarch. Blended formulations incorporated 30% or 50% starch in the presence or absence of poly-(ethylene oxide) (PEO), which enhances the adherence of starch granules to PHBV. These formulations were evaluated for their biodegradability in natural compost by measuring changes in physical and chemical properties over a period of 125 days. The degradation of plastic material, as evidenced by weight loss and deterioration in tensile properties, correlated with the amount of starch present in the blends (neat PHBV 〈 30% starch 〈 50% starch). Incorporation of PEO into starch-PHBV blends had little or no effect on the rate of weight loss. Starch in blends degraded faster than PHBV and it accelerated PHBV degradation. Also, PHBV did not retard starch degradation. After 125 days of exposure to compost, neat PHBV lost 7% of its weight (0.056% weight loss/day), while the PHBV component of a 50% starch blend lost 41% of its weight (0.328% weight loss/day). PHB and PHV moieties within the copolymer degraded at similar rates, regardless of the presence of starch, as determined by 1H-NMR spectroscopy. GPC analyses revealed that, while the number average molecular weight (Mn) of PHBV in all exposed samples decreased, there was no significant difference in this decrease between neat PHBV as opposed to PHBV blended with starch. SEM showed homogeneously distributed starch granules embedded in a PHBV matrix, typical of a filler material. Starch granules were rapidly depleted during exposure to compost, increasing the surface area of the PHBV matrix.
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    Triazine Dispersion and Distribution in the Unsaturated Zone of Drained Soils in the Brie (France) (1998)
    Springer
    Water, air & soil pollution 108 (1998), S. 129-148 
    Details
    ISSN: 1573-2932
    Keywords: biodegradation ; leaching ; soil ; triazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The purpose of this study was to investigate the fate of triazines and their metabolites in the unsaturated zone in the field conditions during a period from the spring sowings to the autumn tillages. The study was performed upon two soils treated for corn culture during the year 1992. The investigations were presented after the wet weather by subsurface drainage and surface runoff. Throughout the 6 months survey, the relative importance of the triazines is by decreasing order: atrazine 〉 simazine 〉 desethylatrazine (DEA). After the application, the herbicides were only found in the first 40 cm of the soil during the dry period of the cultivation. They were dragged towards the depth by percolation water mainly during the first water infiltrations when the drains were set in again in autumn or winter. The losses of herbicides after the cultivation cycle (october) expressed as a ratio of the initial input ranged from 40 to 73% for the atrazine and from 40 to 44% for the simazine and depended on the importance of the application amount. In autumn and winter, the losses originating in percolation were higher than those due to volatilization and/or degradation (abiotic and biodegradation), as the soil conditions were unpropicious to the formation of non-extractable residues.
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    Microbial Degradation of Dimethylsilanediol in Soil (1998)
    Springer
    Water, air & soil pollution 106 (1998), S. 111-122 
    Details
    ISSN: 1573-2932
    Keywords: silicone ; silanol ; environmental ; biodegradation ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dimethylsilanediol (DMSD) is the ultimate hydrolysis product of silicone (polydimethylsiloxane = PDMS) polymer in soil. Our previous paper showed that it would volatilize from soil, and the present study investigates the importance of microbial degradation in removing DMSD from soil. DMSD (14C-labeled) was thus incubated (1 mg kg-1) for 30 wk at 25 °C in soils from a permanent grass field, a corn field, a deciduous woodland, and a pine woodland. Release of14 CO2 varied from 0.4 to 1.6% wk-1. For 3 of the soils, 14CO2 increased with higher microbial biomass, while organisms in the deciduous woodland soil were more active in degrading DMSD than organisms in the other soils. After 30 weeks, most of the remaining 14C in the soil had moved from freely available water extractable to less available acid and base extractable fractions. Similar incubations with 2% plant litter showed extensive transfer of the DMSD into the litter layer. Incubations with a microbial inhibitor showed less DMSD degradation, while cold storage of soils almost completely stopped degradation. These results suggest that microbial degradation is an important mechanism of DMSD loss from soil.
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    Artificial Wetland Performances in the Purification Efficiency of Hydrocarbon Wastewater (1998)
    Springer
    Water, air & soil pollution 104 (1998), S. 313-329 
    Details
    ISSN: 1573-2932
    Keywords: artificial wetlands ; biodegradation ; hydrocarbon ; Lemna minor ; Typha latifolia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract An artificial wetland planted with Typha latifolia was fed during a 360-day experiment with a reconstituted hydrocarbon wastewater (60 ppm, 850 L day−1). Concentrations and chemical composition were periodically monitored. The epuration efficiency was studied together with the accumulation in sediment and the bacterial development. The apparent effluent concentration was below 8 mg L−1 and the decrease in hydrocarbon concentration raised 90%. pH ranged between 6.9 and 8 and Total Suspended Solids (TSS) were below 10 mg L−1. Hydrocarbon amount accumulated in sediment was estimated to be less than 10% of the input amount. We observed a high development of aerobic heterotrophic bacteria (106 bac mL−1) and hydrocarbon-utilizing bacteria (105 bac mL−1), which probably interacted with the plants for the biodegradation of hydrocarbon (in the saturated effluent fraction, normal alkane biodegradation amounted to approximatively 80%). A comparative system with floating plants (Lemma minor), named ‘control bed’, was studied in parellel and showed lower performances.
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    Extractability and Subsequent Biodegradation of PAHs from Contaminated Soil (1998)
    Springer
    Water, air & soil pollution 104 (1998), S. 285-304 
    Details
    ISSN: 1573-2932
    Keywords: biodegradation ; ethanol ; extraction ; PAHs ; polyaromatic hydrocarbons ; solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The biodegradation of polyaromatic hydrocarbons (PAHs) has been well documented; however, the biodegradation of PAHs in contaminated soil has proved to be problematic. Sorption of PAHs to soil over time can significantly decrease their availability for extraction much less than for biodegradation. In this study the ability of various organic solvents to extract PAHs from coal tar-contaminated soil obtained from former manufactured gas plant (MGP) sites was investigated. Solvents investigated included acetone/hexane, dichloromethane, ethanol, methanol, toluene, and water. The extraction of MGP soils with solvents was investigated using soxhlet extraction, multiple soxhlet extractions, sonication, and brief agitation at ambient temperature with a range of solvent concentrations. Of particular interest was the documentation of the recalcitrance of PAHs in weathered MGP soils to extraction and to bioremediation, as well as to demonstrate the ease with which PAHs extracted from these soils can be biodegraded. The efficiency of extraction of PAHs from MGP soils was found to be more dependent upon the choice of solvent. The environmentally-benign solvent ethanol, was shown to be equal to if not better than acetone/hexane (the EPA recommended solvent) for the extraction of PAHs from MGP soils, brief contact/agitation times (minutes) using small quantities of ethanol (2 volumes or less) can achieve nearly quantitative extraction of PAHs from MGP soils. Moreover aqueous slurries of an MGP soils experienced less than 10% biodegradation of PAHs in 14 days while in the same period about 95% biodegradation was acieved using PAHs extracted from this soil by ethanol and subsequently added to aqueous bacterial suspensions.
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    Biodegradation of 4-nitrophenol by indigenous microbial populations in Everglades soils (1997)
    Springer
    Biodegradation 8 (1997), S. 349-356 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; bioremediation ; acclimation ; Everglades ; mineralization ; nitrophenol ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Everglades in South Florida are a unique ecologicalsystem. As a result of the widespread use of pesticides andherbicides in agricultural areas upstream from these wetlands,there is a serious potential for pollution problems in theEverglades. The purpose of this study was to evaluate theability of indigenous microbial populations to degradexenobiotic organic compounds introduced by agricultural andother activities. Such biodegradation may facilitate theremediation of contaminated soils and water in the Everglades.The model compound selected in this study is 4-nitrophenol, achemical commonly used in the manufacture of pesticides. Themineralization of 4-nitrophenol at various concentrations wasstudied in soils collected from the Everglades. Atconcentrations of 10 and 100 µg/g soil, considerablemineralization occurred within a week. At a higherconcentration, i.e., 10 mg/g soil, however, no mineralizationof 4-nitrophenol occurred over a 4-month period; such a highconcentration apparently produced an inhibitory effect. Therate and extent of 4-nitrophenol mineralization was enhancedon inoculation with previously isolated nitrophenol-degradingmicroorganisms. The maximum mineralization extent measured,however, was less than 30% suggesting conversion to biomassand/or unidentified intermediate products. These resultsindicate the potential for natural mechanisms to mitigate theadverse effects of xenobiotic pollutants in a complex systemsuch as the Everglades.
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    Biodegradation of alkylpyridines by bacteria isolated from a polluted subsurface (1997)
    Springer
    Biodegradation 8 (1997), S. 357-361 
    Details
    ISSN: 1572-9729
    Keywords: alkylpyridine ; subsurface bacteria ; biodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten bacterial strains were isolated fromalkylpyridine polluted sediments 7.6 m below thesurface. These strains were able to degrade 11different alkylpyridine isomers. Degradation ratesdepended on number and position of the alkyl group. Isomers with an alkyl group at position 3 were moreresistant to microbial attack. Of the 10 strains, 6isolates were selected for detailed study. Theseisolates mineralized the isomers to CO2,NH4 +, and biomass. All strains weregram-negative rods with a strict aerobic metabolism. Characterization of physiological and biochemicalproperties revealed similarity between strains. Eeachstrain however, had a limited substrate range whichenabled it to degrade no more than 2 to 3 compounds ofthe 14 alkylpyridine isomers tested. Examination ofthe genetic variability among cultures with therandomly amplified polymorphic DNA technique revealedhigh levels of genomic DNA polymorphism. The highestsimilarity between 2 strains (0.653) was observedbetween 2-picoline and 3-picoline degrading cultures. The molecular basis of the differences in substratespecificity is under investigation.
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    A Model for diffusion controlled bioavailability of crude oil components (1997)
    Springer
    Biodegradation 8 (1997), S. 287-296 
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    ISSN: 1572-9729
    Keywords: asphaltene ; bioavailability ; biodegradation ; crude oil ; diffusivity ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Crude oil is a complex mixture ofseveral different structural classes of compoundsincluding alkanes, aromatics, heterocyclic polarcompounds, and asphaltenes. The rate and extent ofmicrobial degradation of crude oil depends on theinteraction between the physical and biochemicalproperties of the biodegradable compounds and theirinteractions with the non-biodegradable fraction. Inthis study we have systematically altered theconcentration of non-biodegradable material in thecrude oil and analyzed its impact on transport of thebiodegradable components of crude oil to themicroorganisms. We have also developed a mathematicalmodel that explains and accounts for the dependence ofbiodegradation of crude oil through a putativebioavailability parameter. Experimental resultsindicate that as the asphaltene concentration in oilincreases, the maximum oxygen uptake in respirometersdecreases. The mathematically fitted bioavailabilityparameter of degradable components of oil alsodecreases as the asphaltene concentration increases.
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    Biodegradation of dissolved jet fuel in chemostat by a mixed bacterial culture isolated from a heavily polluted site (1997)
    Springer
    Biodegradation 8 (1997), S. 363-369 
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    ISSN: 1572-9729
    Keywords: biodegradation ; BTEX ; kerosene ; residual concentration ; volatilisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A mixed bacterial culture capable of biodegrading of jet fuel was isolated from a heavily polluted site in Tapa, Estonia. Residual concentrations of pollutants in the chemostat culture were determined. The total residual concentrations of dissolved jet fuel in culture medium were 0.42 and 2.1 μg l-1 at the dilution rates 0.1 and 0.17 h-1respectively. Benzene, toluene, ethylbenzene, and xylenes were completely degraded and thus not detected in culture broth (detection limit 0.1 μg l-1)at the dilution rates 0.1 and 0.17 h-1. The values of apparent substrate saturation constant(KSapp) in multisubstrate growth conditions were estimated from the experimental data. The residual concentrations satisfy the regulations in the Republic of Estonia for petroleum hydrocarbons (0.00 mg l-1 – ‘very good’). Results obtained indicate that use of the biodegradation could be sufficient for the treatment of polluted with kerosene-type jet fuel groundwater up to the acceptable quality.
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    Prevalence of monochloroacetate degrading genotypes among soil isolates of Pseudomonas (1997)
    Springer
    Biodegradation 8 (1997), S. 371-377 
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    ISSN: 1572-9729
    Keywords: biodegradation ; dehalogenase ; monochloroacetate ; Pseudomonas sp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study reports the isolation of Pseudomonas sp strains with monochloroacetate (MCA) degradation function, from uncontaminated soil, and the use of Southern blot hybridization technique to detect MCA degrading catabolic genes and their divergence. Based on their capacity to remove Cl- from MCA in a minimal medium containing 185 ppm Cl-, the strains were classified into three groups: poor degraders (Cl- release between 0–15 ppm), medium degraders (Cl- release between 16–30 ppm), and high degraders (Cl- release between 31–45 ppm).We have applied a gene probe assay for determining the diversity of MCA degradative genotypes of 61 strains. Two different gene probes, dehCI and dehCII were used in Southern blot hybridization assays. Majority of the DNA samples that produced signals on the membrane blots (18 out of 24)hybridized with only dehCI DNA probe, while 6strains hybridized with only dehCII probe. On the other hand, 37 isolates did not hybridize to either of the gene probes used. The results indicated the high specificity of the DNA hybridization method and the divergence of metabolic functions and/or genotypes among the native MCA-degrading Pseudomonas sp. populations in the soil.
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    Microbiological aspects of surfactant use for biological soil remediation (1997)
    Springer
    Biodegradation 8 (1997), S. 401-417 
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    ISSN: 1572-9729
    Keywords: bioavailability ; biodegradation ; bioremediation ; mass transfer ; soil sanitation ; surfactants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Biodegradation of hydrophobic organic compounds in polluted soil is a process involving interactions among soil particles, pollutants, water, and micro-organisms. Surface-active agents or surfactants are compounds that may affect these interactions, and the use of these compounds may be a means of overcoming the problem of limited bioavailability of hydrophobic organic pollutants in biological soil remediation. The effects of surfactants on the physiology of micro-organisms range from inhibition of growth due to surfactant toxicity to stimulation of growth caused by the use of surfactants as a co-substrate. The most important effect of surfactants on the interactions among soil and pollutant is stimulation of mass transport of the pollutant from the soil to the aqueous phase. This can be caused by three different mechanisms: emulsification of liquid pollutant, micellar solubilisation, and facilitated transport. The importance of these mechanisms with respect to the effect of surfactants on bioavailability is reviewed for hydrophobic organic pollutants present in different physical states. The complexity of the effect of surfactants on pollutant bioavailability is reflected by the results in the literature, which range from stimulation to inhibition of desorption and biodegradation of polluting compounds. No general trends can be found in these results. Therefore, more research is necessary to make the application of surfactants a standard tool in biological soil remediation.
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    Indirect bioremediation: biodegradation of hydrocarbons on a commercial sorbent (1997)
    Springer
    Biodegradation 8 (1997), S. 15-19 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; crude oil ; hexadecane ; phenanthrene ; sorbent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Urea-formaldehyde polymer is currently used as asorbent for containment and clean up of hydrocarbons. The aerobic biodegradability of this polymer andhydrocarbons sorbed to the polymer were tested. Soilmicroorganisms readily grew on the polymer, and twoorganisms, a bacterium and a fungus, capable of growthon the polymer were isolated. However, biodegradationof the polymer was very slow and possibly incomplete. Biodegradation of the polymer was evident as a changein appearance of the polymer, but disappearance of thepolymer was not detectable in liquid culturesincubated for six months or soil cultures incubatedfor one month. Destruction of the polymer by soilmicroorganisms at ambient temperature does not appearto be practical. Degradation of 14C-labeledhexadecane and phenanthrene mixed with crude oil inliquid cultures inoculated with soil microorganismswas used as an estimate of general hydrocarbondegradation. When nitrogen was not limiting, therates of hexadecane and phenanthrene degradation werethe same, whether those hydrocarbons were sorbed tothe polymer or not sorbed. When nitrogen waslimiting, the polymer stimulated the rate ofhexadecane degradation but not the rate ofphenanthrene degradation. The polymer may stimulatehexadecane degradation by serving as a source ofnitrogen. However, optimal degradation of sorbedhydrocarbons requires nitrogen addition. The resultssuggest that it may be feasible to decontaminate spentpolymer by biodegradation of sorbed hydrocarbons.
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    Biodegradation of the chlorophenoxy herbicide (R)-(+)-mecoprop by Alcaligenes denitrificans (1997)
    Springer
    Biodegradation 8 (1997), S. 43-52 
    Details
    ISSN: 1572-9729
    Keywords: Alcaligenes denitrificans ; biodegradation ; chloroaromatic ; mecoprop (R)-(+)-2(2-methyl-4-chlorophenoxy)propionic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An Alcaligenes denitrificans strain capable of utilizing theherbicide (R)-(+)-2(2-methyl-4-chlorophenoxy)propionicacid (mecoprop) as a sole carbon source was isolated fromsoil and cultured in liquid medium. Crude cell extracts of thebacterium were utilized in spectrophotometric assays toelucidate a biochemical pathway for degradation ofmecoprop. Results indicated a reaction sequence analogousto the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D).GC-MS analysis provided direct evidence for thebiotransformation of mecoprop to the transient metabolite4-chloro-2-methylphenol (MCP). No NADPH-dependentactivity was observed during this reaction. Pyruvate wasverified as the second product derived from the aliphatic sidechain of mecoprop. MCP was subsequently transformed to asubstituted catechol by an NADPH-dependentmonooxygenase. When grown on mecoprop, A.denitrificans was adapted to oxidize catechol and its 4- and3-methylated derivatives indicating the broad substratespecificity of catechol dioxygenase. The microorganism wasdemonstrated to adopt the ortho mechanism of aromaticcleavage which resulted in the formation of2-methyl-4-carboxymethylene but-2-en-4-olide, a reactionintermediate of the β-ketoadipate pathway.
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    Biodegradation of benzene, toluene and naphthalene in soil-water slurry microcosms (1997)
    Springer
    Biodegradation 8 (1997), S. 167-175 
    Details
    ISSN: 1572-9729
    Keywords: benzene ; bioavailability ; biodegradation ; naphthalene ; sorption ; toluene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aerobic biodegradation of benzene, toluene andnaphthalene was studied in pre-equilibrated soil-waterslurry microcosms. The experiments were designed tosimulate biodegradation at waste sites where sorptionreaches equilibrium before biodegradation becomesimportant. Rates of biodegradation were reduced by thepresence of soil. For example, nearly completenaphthalene biodegradation (1.28 mg/L) by indigenoussoil bacteria occurred within 60 hours in aqueoussolution (soil-free) while it took two weeks todegrade the same amount in the presence of 0.47 kgsoil/L of water. The rate of biodegradation wasobserved to decrease with increasing organic compoundhydrophobicity, soil/water ratio, soil particle size,and soil organic carbon content. These resultsclearly indicate that the rate of biodegradation isaffected by both the extent and rate of sorption. Further analysis suggests that mass transfer couldcontrol the performance of in situ bioremediation forhighly hydrophobic organic contaminants which exhibita large extent of sorption and slow rate ofdesorption.
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    Terpene-utilizing isolates and their relevance to enhanced biotransformation of polychlorinated biphenyls in soil (1997)
    Springer
    Biodegradation 8 (1997), S. 153-158 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; PCB ; Aroclor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Orange peels, eucalyptus leaves, pine needles and ivy leaves were addedseparately to soil spiked with Aroclor 1242 (100 mgkg-1.Polychorinated biphenyls (PCBs) disappeared after six months in all theamended soils, but not in unamended soils. Although biphenyl was not addedto any of the soils, all four amended soils had much higher levels(108/g) of biphenyl-utilizing bacteria than the unamendedcontrol (103/g). Ten random isolates obtained from these soilswere identified as coryneform bacteria. Five isolates, that were distinctlydifferent, were studied further with respect to growth on pure terpenes andmetabolism of PCBs. The most effective strains were Cellulomonas sp. T109and R. rhodochrous T100, which metabolized 83% and 80% ofAroclor 1242, respectively, during a six day period of growth on cymene andlimonene, respectively. The bphA gene, cloned as a 2.8 Kb Sa/I fragment ofpAW6194 from cbpA (Walia et al. 1990) hybridized to total DNA of allcoryneform isolates, and to the well-established PCB degrader Rhodococcusgloberulus. In contrast, a 5 Kb XhoI-SmaI fragment of the bphA gene(Furukawa & Miyazaki 1986) did not show any homology to the genomic DNAof any of the isolates or to R. globerulus, but did hybridize to two otherwell-known PCB degraders Pseudomonas sp. LB400, and Alcaligenes eutrophusH850. The data presented herein indicate that terpenes may be naturalsubstrates for biphenyl-degrading bacteria and may enhance substantialtransformation of Aroclor 1242.
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    Implementation of natural attenuation at a JP-4 jet fuel release after active remediation (1997)
    Springer
    Biodegradation 8 (1997), S. 265-273 
    Details
    ISSN: 1572-9729
    Keywords: natural attenuation ; biodegradation ; hydrocarbon ; groundwater ; BTEX ; MTBE ; site characterization ; fate and transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract After eighteen months of active remediation at a JP-4 jet-fuel spill, aresidual of unremediated hydrocarbon remained. Further site characterizationwas conducted to evaluate the contribution of natural attenuation to controlexposure to hazards associated with the residual contamination in thesubsurface. Activities included the detailed characterization ofground-water flow through the spill; the distribution of fuel contaminantsin groundwater; and the analysis of soluble electron acceptors moving intothe spill from upgradient. These activities allowed a rigorous evaluation ofthe transport of contaminants from the spill to the receptor of groundwater,the Pasquotank River. The transport of dissolved contaminants of concern,that is benzene, toluene, ethyl benzene, xylene isomers (BTEX) andmethyl-tertiary-butyl ether (MTBE), into the river from the source area wascontrolled by equilibrium dissolution from the fuel spill to the adjacentgroundwater, diffusion in groundwater from the spill to permeable layers inthe aquifer, and advective transport in the permeable layers. The estimatedyearly loading of BTEX compounds and MTBE into the receptor was trivial evenwithout considering biological degradation. The biodegradation ofhydrocarbon dissolved in groundwater through aerobic respiration,denitrification, sulfate reduction, and iron reduction was estimated fromchanges in ground-water chemistry along the flow path. The concentrations oftarget components in permanent monitoring wells continue to decline overtime. Long term monitoring will ensure that the plume is under control, andno further active remediation is required.
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    Ring cleavage of sulfur heterocycles: how does it happen? (1997)
    Springer
    Biodegradation 8 (1997), S. 297-311 
    Details
    ISSN: 1572-9729
    Keywords: benzothiophenes ; biodegradation ; biodesulfurization ; dibenzothiophenes ; thiacycloalkanes ; thiophenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sulfur heterocycles are common constituents ofpetroleum and liquids derived from coal, and they arefound in some secondary metabolites of microorganismsand plants. They exist primarily as saturated ringsand thiophenes. There are two major objectives drivinginvestigations of the microbial metabolism oforganosulfur compounds. One is the quest to develop aprocess for biodesulfurization of fossil fuels, andthe other is to understand the fates of organosulfurcompounds in petroleum- or creosote-contaminatedenvironments which is important in assessingbioremediation processes. For these processes to besuccessful, cleavage of different types of sulfurheterocyclic rings is paramount. This paper reviewsthe evidence for microbial ring cleavage of a varietyof organosulfur compounds and discusses the fewwell-studied cases which have shown that the C–S bondis most susceptible to breakage leading to disruptionof the ring. In most cases, the introduction of one ormore oxygen atom(s) onto the adjacent C atom and/oronto the S atom weakens the C–S bond, facilitating itscleavage. Although much is known about the thiophenering cleavage in dibenzothiophene, there is still agreat deal to be learned about the cleavage of othersulfur heterocycles.
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    Enhancement of biodegradation of phenol and a nongrowth substrate 4-chlorophenol by medium augmentation with conventional carbon sources (1997)
    Springer
    Biodegradation 8 (1997), S. 329-338 
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    ISSN: 1572-9729
    Keywords: biodegradation ; cometabolism ; nongrowth substrate ; conventional carbon sources ; inhibition ; pH regulation ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The enhancement of biodegradation of phenol and4-chlorophenol (4-cp) as a cometabolised compound byPseudomonas putida ATCC 49451 was accomplishedby augmenting the medium with conventional carbonsources such as sodium glutamate and glucose. Comparedwith phenol as the sole carbon source, the addition of1 gl-1 sodium glutamate increased the toxicitytolerance of cells toward 4-cp and significantlyimproved the biodegradation rates of both phenol and4-cp even when the initial concentration of 4-cp wasas high as 200 mgl-1. On the other hand,supplementation of glucose caused a significant dropin the medium pH from 7.2 to 4.3 resulting in areduction of degradation rate, leaving a considerableamount of 4-cp undegraded when the initialconcentration of 4-cp was higher than 100 mgl-1.By regulating the pH of the medium, however,enhancement of degradation rates of phenol and 4-cp inthe presence of glucose was achieved with aconcomitant complete degradation of phenol and 4-cp.
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    The effect of inorganic and organic supplements on the microbial degradation of phenanthrene and pyrene in soils (1997)
    Springer
    Biodegradation 8 (1997), S. 1-13 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; PAH ; phenanthrene ; pyrene ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of several bioremediation stimulants, including potentialmetabolism pathway inducers, inorganic/organic nutrients, and surfactants onthe metabolism of phenanthrene and pyrene, as well as the populationdynamics of PAH degrading microorganisms was examined in five soils withdiffering background PAH concentrations, exposure histories and physicalproperties. Most of the supplements either had no significant effect ordecreased the mineralization of [14C]-phenanthrene and[14C]-pyrene in soil slurry microcosms. The effect of aparticular supplement, however, was often not uniform within or acrosssoils. Decreased mineralization of [14C]-phenanthrene and[14C]-pyrene was usually due to either preferential use of thesupplement as carbon source and/or stimulation of non-PAH degradingmicroorganisms. Many of the supplements increased populations ofheterotrophic microorganisms, as measured by plate counts, but did notincrease populations of phenanthrene degrading microorganisms, as measuredby the [14C]-PAH mineralization MPN analysis or cellularincorporation of [14C]-PAH. These results suggest that the PAHdegrading community at each site may be unique in their response tomaterials added in an attempt to stimulate PAH degradation. Thecharacteristics of the site, including exposure history, soil type, andtemporal variation may all influence their response.
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    URL: http://dx.doi.org/10.1023/A:1008258720649
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    Evaluation of biodegradability of poly(ε-caprolactone)/poly(ethylene terephthalate) blends (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 37-50 
    Details
    ISSN: 1572-8900
    Keywords: Poly(ethylene terephthalate) ; poly(ε-caprolactone) ; blends ; biodegradation ; composting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The results of an investigation aimed at evaluation of the biodegradability of blends of poly(ε-caprolactone) (PCL) with poly(ethylene terephthalate) (PET) as the major component are reported. Specimens of the blends, as melt extruded films and/or powders, were submitted to degradation tests under different environmental conditions including full-scale composting, soil burial, bench-scale accelerated aerobic degradation, and exposure to axenic cultures and esterolytic enzymes. Indications have been gained that blending in the melt gives rise to insertion of PCL segments in the PET chain. Copolymers thus attained acted as macromolecular compatibilizers, allowing for a complete miscibility of PCL and PET. The biodegradation detected on the blend samples was, however, well below the values expected from chemical composition and behavior of individual homopolymers under the same environmental conditions. The presence of PET as the major component in PET/PCL blends apparently reduces the propensity of PCL to be degraded, at least in the investigated composition range. The degradation data collected under different environmental conditions indicate that the full-scale composting system is the most efficient among the tested degradation procedures.
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    URL: http://dx.doi.org/10.1007/BF02083881
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    The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 179-195 
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    ISSN: 1572-8900
    Keywords: Cellulose acetate ; composting ; radiochemical labeling ; biodegradation ; blend miscibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.
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    URL: http://dx.doi.org/10.1007/BF02067452
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    Preparation conditions and swelling equilibria of biodegradable hydrogels prepared from microbial poly(γ-glutamic acid) and poly(ε-lysine) (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 123-129 
    Details
    ISSN: 1572-8900
    Keywords: Poly(γ-glutamic acid) ; poly(ε-lysine) ; hydrogel ; biodegradation ; enzymatic degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Biodegradable hydrogels prepared by γ-irradiation from microbial poly(amino acid)s are reviewed. pH-sensitive hydrogels were prepared by means of γ-irradiation of poly(γ-glutamic acid) (PGA) produced byBacillus subtilis IFO3335 and poly(ε-lysine) (PL) produced byStreptomyces albulus in aqueous solutions. The preparation conditions, swelling equilibria, hydrolytic degradation, and enzymatic degradation of these hydrogels were studied. A hydrogel with a wide variety of swelling behaviors has been produced by γ-irradiation from a mixture solution of PGA and PL.
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    URL: http://dx.doi.org/10.1007/BF02074873
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    Biodegradation of atrazine in surface soils and subsurface sediments collected from an agricultural research farm (1996)
    Springer
    Biodegradation 7 (1996), S. 137-149 
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    ISSN: 1572-9729
    Keywords: atrazine ; bacteria ; biodegradation ; mineralization ; sorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of the present study was to assess atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) mineralization by indigenous microbial communities and to investigate constraints associated with atrazine biodegradation in environmental samples collected from surface soil and subsurface zones at an agricultural site in Ohio. Atrazine mineralization in soil and sediment samples was monitored as 14CO2 evolution in biometers which were amended with 14C-labeled atrazine. Variables of interest were the position of the label ([U-14C-ring]-atrazine and [2-14C-ethyl]-atrazine), incubation temperature (25°C and 10°C), inoculation with a previously characterized atrazine-mineralizing bacterial isolate (M91-3), and the effect of sterilization prior to inoculation. In uninoculated biometers, mineralization rate constants declined with increasing sample depth. First-order mineralization rate constants were somewhat lower for [2-14C-ethyl]-atrazine when compared to those of [U-14C-ring]-atrazine. Moreover, the total amount of 14CO2 released was less with [2-14C-ethyl]-atrazine. Mineralization at 10°C was slow and linear. In inoculated biometers, less 14CO2 was released in [2-14C-ethyl]-atrazine experiments as compared with [U-14C-ring]-atrazine probably as a result of assimilatory incorporation of 14C into biomass. The mineralization rate constants (k) and overall extents of mineralization (P max ) were higher in biometers that were not sterilized prior to inoculation, suggesting that the native microbial populations in the sediments were contributing to the overall release of 14CO2 from [U-14C-ring]-atrazine and [2-14C-ethyl]-atrazine. A positive correlation between k and aqueous phase atrazine concentrations (C eq ) in the biometers was observed at 25°C, suggesting that sorption of atrazine influenced mineralization rates. The sorption effect on atrazine mineralization was greatly diminished at 10°C. It was concluded that sorption can limit biodegradation rates of weakly-sorbing solutes at high solid-to-solution ratios and at ambient surface temperatures if an active degrading population is present. Under vadose zone and subsurface aquifer conditions, however, low temperatures and the lack of degrading organisms are likely to be primary factors limiting the biodegradation of atrazine.
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    URL: http://dx.doi.org/10.1007/BF00114626
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    Degradation of 4-aminobenzenesulfonate by a two-species bacterial coculture (1996)
    Springer
    Biodegradation 7 (1996), S. 223-229 
    Details
    ISSN: 1572-9729
    Keywords: Agrobacterium radiobacter ; 4-aminobenzenesulfonate ; biodegradation ; cross-feeding ; Hydrogenophaga palleronii ; mixed culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mutualistic interactions in a 4-aminobenzenesulfonate (sulfanilate) degrading mixed bacterial culture were studied. This coculture consisted of Hydrogenophaga palleronii strain S1 and Agrobacterium radiobacter strain S2. In this coculture only strain S1 desaminated sulfanilate to catechol-4-sulfonate, which did not accumulate in the medium but served as growth substrate for strain S2. During growth in batch culture with sulfanilate as sole source of carbon, energy, nitrogen and sulfur, the relative cell numbers (colony forming units) of both strains were almost constant. None of the strains reached a cell number which was more than threefold higher than the cell number of the second strain. A mineral medium with sulfanilate was inoculated with different relative cell numbers of both strains (relative number of colony forming units S1:S2 2200:1 to 1:500). In all cases, growth was found and the proportion of both strains moved towards an about equal value of about 3:1 (strain S1:strain S2). In contrast to the coculture, strain S1 did not grow in a mineral medium in axenic culture with 4-aminobenzenesulfonate or any other simple organic compound tested. A sterile culture supernatant from strain S2 enabled strain S1 to grow with 4-aminobenzenesulfonate. The same growth promoting effect was found after the addition of a combination of 4-aminobenzoate, biotin and vitamin B12. Strain S1 grew with 4-aminobenzenesulfonate plus the three vitamins with about the same growth rate as the mixed culture in a mineral medium. When (resting) cells of strain S1 were incubated in a pure mineral medium with sulfanilate, up to 30% of the oxidized sulfanilate accumulated as catechol-4-sulfonate in the culture medium. In contrast, only minor amounts of catechol-4-sulfonate accumulated when strain S1 was grown with 4ABS in the presence of the vitamins.
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    URL: http://dx.doi.org/10.1007/BF00058181
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    The anaerobic biodegradation of diethanolamine by a nitrate reducing bacterium (1996)
    Springer
    Biodegradation 7 (1996), S. 183-189 
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    ISSN: 1572-9729
    Keywords: biodegradation ; diethanolamine ; ethanolamines ; nitrate reduction ; amine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The ability of bacterial cultures to degrade diethanolamine under anoxic conditions with nitrate as an electron acceptor was investigated. A mixed culture capable of anaerobic degradation of diethanolamine was obtained from river sediments by enrichment culture. From this a single bacterial strain was isolated which could use diethanolamine, monoethanolamine, triethanolamine and N-methyl diethanolamine as its sole carbon and energy sources either aerobically or anaerobically. Growth on diethanolamine was faster in the absence of oxygen. The accumulation of possible metabolites in the culture medium was determined as was the ability to grow on certain putative intermediates in the degradation of diethanolamine. A possible pathway for the degradation of ethanolamines by this organism is suggested.
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    URL: http://dx.doi.org/10.1007/BF00058178
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    Biodegradation of 4-nitroanisole by two Rhodococcus spp. (1996)
    Springer
    Biodegradation 7 (1996), S. 249-255 
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    ISSN: 1572-9729
    Keywords: biodegradation ; O-demethylation ; metabolism ; 4-nitroanisole ; 4-nitrophenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two Rhodococcus strains, R. opacus strain AS2 and R. erythropolis strain AS3, that were able to use 4-nitroanisole as the sole source of carbon and energy, were isolated from environmental samples. The first step of the degradation involved the O-demethylation of 4-nitroanisole to 4-nitrophenol which accumulated transiently in the medium during growth. Oxygen uptake experiments indicated the transformation of 4-nitrophenol to 4-nitrocatechol and 1,2,4-trihydroxybenzene prior to ring cleavage and then subsequent mineralization. The nitro group was removed as nitrite, which accumulated in the medium in stoichiometric amounts. In R. opacus strain AS2 small amounts of hydroquinone were produced by a side reaction, but were not further degraded.
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    URL: http://dx.doi.org/10.1007/BF00058184
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    Biodegradation of rubber particles in soil (1996)
    Springer
    Biodegradation 7 (1996), S. 329-333 
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    ISSN: 1572-9729
    Keywords: biodegradation ; modelling ; rubber ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The biodegradation of rubber particles in rubber-soil mixtures at different rubber contents was monitored by the carbon dioxide production. The cumulative carbon dioxide production was modelled according to a two parameter exponential function. The model provides an excellent fit (R2〉0.98) for the observed data. The two parameters yield a reliable estimate of the half-life for the process observed, but estimation of the true half-life of rubber in soil will need more research.
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    URL: http://dx.doi.org/10.1007/BF00115746
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    Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions (1996)
    Springer
    Biodegradation 7 (1996), S. 345-352 
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    ISSN: 1572-9729
    Keywords: biodegradation ; methane formation ; phthalic acid esters ; landfills ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microoganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade PAEs compared with those developing in a biogas reactor.
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    URL: http://dx.doi.org/10.1007/BF00115748
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    Isolation from coastal sea water and characterization of bacterial strains involved in non-ionic surfactant degradation (1996)
    Springer
    Biodegradation 7 (1996), S. 369-375 
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    ISSN: 1572-9729
    Keywords: bacteria ; biodegradation ; marine environment ; non-ionic surfactant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A bacterial community degrading branched alkylphenol ethoxylate (APE) was selected from coastal sea water intermittently polluted by urban sewage. This community degraded more than 99% of a standard surfactant, TRITON X 100, but I.R. analysis of the remaining compound showed the accumulation of APE2 (alkylphenol with a two units length ethoxylated chain) which seemed very recalcitrant to further biodegradation. Twenty-five strains were isolated from this community, essentially Gram negative and were related to Pseudomonas, Oceanospirillum or Deleya genera. Among these strains, only four were able to degrade APE9–10 (TRITON X 100). They were related to the Pseudomonas genus and were of marine origin. Pure cultures performed with these strains on TRITON X 100 gave APE5 and APE4 as end products. These products were further degraded to APE2 by two other strains unable to degrade the initial surfactant.
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    Biodegradability of diesel oil (1996)
    Springer
    Biodegradation 7 (1996), S. 73-81 
    Details
    ISSN: 1572-9729
    Keywords: diesel oil ; biodegradation ; CSTR ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In batch culture diesel oil was degraded rapidly, with a maximum growth rate (for a consortium of microorganisms) of 0.55 h-1. The corresponding yield Y SX was 0.1 Cmol/Cmol. In a continuous stirred tank reactor the maximum dilution rate was about 0.25 h-1, with a yield of 0.3 Cmol/Cmol. With a residence time of 1 day 82% of the influent oil was degraded. In the batch reactor, of the mixture of linear and branched alkanes the linear alkanes were degraded fastest and with the highest yield. Only after most of the linear alkanes had disappeared were the branched alkanes consumed. In a CSTR a large part of the branched alkanes was not degraded.
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    Aerobic degradation of polychlorinated biphenyls by Alcaligenes sp. JB1: metabolites and enzymes (1996)
    Springer
    Biodegradation 7 (1996), S. 435-443 
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    ISSN: 1572-9729
    Keywords: aerobic ; biodegradation ; enzymes ; induction ; polychlorinated biphenyls ; resting-cell assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In contrast to the degradation of penta-and hexachlorobiphenyls in chemostat cultures, the metabolism of PCBs by Alcaligenes sp. JB1 was shown to be restricted to PCBs with up to four chlorine substituents in resting-cell assays. Among these, the PCB congeners containing ortho chlorine substituents on both phenyl rings were found to be least degraded. Monochloro-benzoates and dichlorobenzoates were detected as metabolites. Resting cell assays with chlorobenzoates showed that JB1 could metabolize all three monochlorobenzoates and dichlorobenzoates containing only meta and para chlorine substituents, but not dichlorobenzoates possessing an ortho chlorine substituent. In enzyme activity assays, meta cleaving 2,3-dihydroxybiphenyl 1,2-dioxygenase and catechol 2,3-dioxygenase activities were constitutive, whereas benzoate dioxygenase and ortho cleaving catechol 1,2-dioxygenase activities were induced by their substrates. No activity was found for pyrocatechase II, the enzyme that is specific for chlorocatechols. The data suggest that complete mineralization of PCBs with three or more chlorine substituents by Alcaligenes sp. JB1 is unlikely.
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    Assessing mineralization rates of petroleum hydrocarbons in soils in relation to environmental factors and experimental scale (1996)
    Springer
    Biodegradation 7 (1996), S. 487-500 
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    ISSN: 1572-9729
    Keywords: biodegradation ; bioremediation ; mathematical modeling ; soil respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mineralization rates of non-volatile petroleum hydrocarbons (HCs) in five different oil-contaminated soils with initial HC contents ranging from 0.1 to 13 g kg-1 are estimated as a function of environmental factors. The aim of the study is threefold, (i) to study the relevance of environmental factors that may influence the mineralization rate, (ii) to compare mineralization rates estimated in two experiments at different scales, after standardizing them to environmental reference conditions, (iii) to evaluate the CO2 production rate as a measure for the mineralization rate of HCs. Experiments were performed at laboratory scale (30–50 cm3 soil volume) in closed-jars under constant environmental conditions and in lysimeters (0.81 m3 soil volume) under dynamic climatic and hydrological conditions. A biodegradation model, coupled to transport models for soil heat, water, and gas dynamics is employed for data interpretation. The transport models are used to simulate the environmental conditions that influence the mineralization rate in the non-steady lysimeter experiments. The results show that temperature, O2 concentration and HC content have an effect on the mineralization rates. Water content could not be identified as a direct governing environmental factor. However, an indirect effect of water content is that it influences the effective gas diffusion coefficient in soils. The CO2 production rate seems to be a good quantity to express the mineralization rate of HCs for HC contents〉1 g kg-1. Measured CO2 production rates standardized to reference conditions are similar for the two different experimental scales. This demonstrates that the usage of biodegradation rates obtained in the laboratory to predict the biodegradation rates under field conditions is sound, as long as the differences in environmental conditions have been taken into account.
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    Enhanced biodegradation of diesel fuel through the addition of particulate organic carbon and inorganic nutrients in coastal marine waters (1996)
    Springer
    Biodegradation 7 (1996), S. 239-247 
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    ISSN: 1572-9729
    Keywords: biodegradation ; diesel fuel ; marine & particulate organic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Diesel fuel pollution in coastal waters, resulting from recreational boating and commercial shipping operations, is common and can adversely affect marine biota. The purpose of this study was to examine the effect of additions of particulate organic carbon (POC) in the form of naturally-occurring marsh grass (Spartina alterniflora), inorganic nutrients (nitrogen and phosphorus), inert particles, and dissolved organic carbon (DOC) on diesel fuel biodegradation and to attempt to formulate an effective bioremedial treatment for small diesel fuel spills in marine waters. Various combinations of treatments were added to water samples from a coastal marina to stimulate diesel fuel biodegradation. Diesel fuel was added in concentrations approximating those found in a spill and biodegradation of straight chain aliphatic constituents was estimated by measuring mineralization of 14C hexadecane added to diesel fuel. All treatments that included POC showed stimulation of biodegradation. However, the addition of inert particles (glass fiber filters and nylon screening) caused no stimulation of biodegradation. The addition of nitrogen and phosphorus alone did not result in stimulation of biodegradation, but nitrogen and Spartina (although not phosphorus and Spartina) did result in stimulation above that of Spartina alone. Maximum biodegradation rates were obtained by the addition of the Spartina POC, ammonium, and phosphate. The addition of mannitol, a labile DOC source with POC and phosphate resulted in a decrease in diesel fuel biodegradation as compared to POC and phosphate alone. The seasonal pattern of diesel fuel biodegradation showed a maximum in the summer and a minimum in the winter. Therefore, of the treatments tested, the most effective for bioremediation of diesel fuel in marine waters is the addition of POC, nitrogen, and phosphorus.
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    Degradation of olestra, a non caloric fat replacer, by microorganisms isolated from activated sludge and other environments (1996)
    Springer
    Biodegradation 7 (1996), S. 257-265 
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    ISSN: 1572-9729
    Keywords: biodegradation ; sewage ; soil ; Pseudomonas aeruginosa ; fat replacement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Olestra is a non-caloric fat substitute consisting of fatty acids esterified to sucrose. Previous work has shown that olestra is not metabolized in the gut and is excreted unmodified in human feces. To better understand the fate of olestra in engineered and natural environments, aerobic bacteria and fungi that degrade olestra were enriched from sewage sludges, soils and municipal solid waste compost not previously exposed to olestra. Various mixed and pure cultures were obtained from these sources which were able to utilize olestra as a sole carbon and energy source. The fastest growing enrichment was obtained from activated sludge and later yielded an olestra-degrading pure culture of Pseudomonas aeruginosa. This mixed culture extensively degraded both 14C-fatty acid labeled olestra and 14C-sucrose labeled olestra during 8 days of incubation. Longer-term incubation with pure cultures of P. aeruginosa demonstrated that 〉98% of 14C-sucrose labeled olestra and 〉72% of 14C-fatty acid labeled olestra was mineralized to CO2 after 69 days. These results indicate that olestra degraders are present in environments not previously exposed to olestra and that olestra can serve as a sole carbon and energy source. Furthermore, a common bacterial species was isolated from activated sludge and shown to have the ability to degrade olestra.
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    Screening of bacteria, isolated from PAH-contaminated soils, for production of biosurfactants and bioemulsifiers (1996)
    Springer
    Biodegradation 7 (1996), S. 415-423 
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    ISSN: 1572-9729
    Keywords: biodegradation ; bioemulsifier ; biosurfactant ; polyaromatic hydrocarbons ; soil bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fifty-seven bacterial strains were isolated from PAH-contaminated soils using PAH-amended minimal medium. The isolates were screened for their production of biosurfactants and bioemulsifiers when grown in liquid media containing selected PAHs. The results suggest that many, but not all, of the isolates are able to produce biosurfactants or bioemulsifiers under the experimental conditions. The majority of the strains isolated on phenanthrene, pyrene, and fluoranthene were better emulsifiers than surface tension reducers and the stability of the formed emulsions was in general high. The strains isolated on anthracene were in general better in lowering the surface tension than in forming emulsions. In all strains, reduction of surface tension and emulsion formation did not correlate. However, in the majority of strains the two factors were associated with the bacterial cell surfaces, rather than the culture supernatants. Nevertheless, supernatants from selected surfactant-producing anthracene isolates increased the aqueous solubility of anthracene. Although a significant potential for surfactant and emulsifier production in the microbiota of the PAH-contaminated soils was found in this study, the ability of individual strains to mineralize PAHs did not coincide with production of surface-active compounds.
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    Degradation of bis(2-ethylhexyl) phthalate constituents under methanogenic conditions (1996)
    Springer
    Biodegradation 7 (1996), S. 501-506 
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    ISSN: 1572-9729
    Keywords: biodegradation ; Bis(2-ethylhexyl) phthalate ; 2-ethylhexanol ; 2-ethylhexanoic acid ; methane formation ; mono(2-ethylhexyl) phthalate ; phthalic acid esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degradation of bis(2-ethylhexyl) phthalate (DEHP) and its intermediary hydrolysis products 2-ethylhexanol (2-EH) and mono(2-ethylhexyl) phthalate (MEHP) was investigated in a methanogenic phthalic acid ester-degrading enrichment culture at 37°C. 2-Ethylhexanoic acid (2-EHA), a plausible degradation product of 2-EH, was also studied. The culture readily degraded 2-EH via 2-EHA to methane which was formed in stoichiometric amounts assuming complete degradation of 2-EH to methane and carbon dioxide. MEHP was degraded to stoichiometric amounts of methane with phthalic acid as a transient intermediate. DEHP remained unaffected throughout the experimental period (330 days).
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    URL: http://dx.doi.org/10.1007/BF00115296
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    Anaerobic microbial degradation of poly (3-hydroxyalkanoates) with various terminal electron acceptors (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 91-102 
    Details
    ISSN: 1572-8900
    Keywords: Poly (3-hydroxyalkanoates) ; poly (3-hydroxybutyrate) ; poly (3-hydroxybutyrate-co-3-hydroxyvalerate) ; biodegradation ; nitrate reduction ; iron reduction ; sulfate reduction ; methanogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The microbial degradation of poly (3-hydroxyalkanoates) (PHAs) under anaerobic conditions with various terminal electron acceptors was examined. Nitrate-reducing consortia were established using activated sludge, and PHAs were shown to be biodegradable under these conditions. A positive correlation between carbon dioxide production and nitrate reduction was demonstrated. Nitrous oxide accumulated as the main N-containing product of nitrate reduction. The amount of PHAs in activated sludge cultures decreased approximately 20% within 40 days of incubation. Attempts were made to establish iron- and sulfate-reducing consortia from spring water, yet it could not be demonstrated that the mixed cultures were capable of degrading PHAs. Pure cultures of iron- and sulfate-reducing bacteria could not utilize PHAs as sole carbon sources. Methanogenic environments sampled included pond sediment and rumen fluid. PHAs were fermented to methane and carbon dioxide after 10 weeks by a sediment consortium, with 43 to 57% of the substrate carbon transformed to methane. Although it could not be demonstrated that PHAs were biodegraded by a rumen fluid consortium, a facultative anaerobic bacterium, identified as aStaphylococcus sp., that could grow on PHAs was isolated from rumen fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02074870
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    Properties and biodegradability of chain-extended copoly(succinic anhydride/ethylene oxide) (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 225-233 
    Details
    ISSN: 1572-8900
    Keywords: Copolyesterether ; succinic anhydride ; chain-extension reaction ; biodegradation ; activated sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Chain-extension reactions were carried out using titanium-iso-propoxide (TIP) as a catalyst for a series of polyesters or copolyesterethers with low molecular weights (M n =1500–10,000) synthesized by the ring-opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO). The copolymers having aM n from 25,000 to 50,000 of different properties were obtained. Both the melting point (T m ) and the fusion heat (δH), which indicate the crystallinity of the copolymers, rose with an increase in SA content in the copolymers. Semitransparent films were prepared by compression molding of the copolymers. The biodegradation of the copolymer films was evaluated by enzymatic hydrolysis by lipases and by an aerobic gas evolution test in standard activated sludge. The hydrolyzability of these copolymers by three kinds of lipases was affected by their copolymer composition SA/EO, form, andM n . The copolyesterether (SA/EO=43/57,M n =48,900) was more easily biodegraded by standard activated sludge compared to the polyester (SA/EO=47/53,M n =36,300).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02070691
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    Measurement of the biodegradation of starch-based materials by enzymatic methods and composting (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 23-29 
    Details
    ISSN: 1572-8900
    Keywords: Composting ; starch-based biopolymers ; enzymatic degradation ; biodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The aim of this study was to evaluate the suitability of in vitro enzymatic methods for assaying the biodegradability of new starch-based biopolymers. The materials studied included commercial starch-based materials and thermoplastic starch films prepared by extrusion from glycerol and native potato starch, native barley starch, or crosslinked amylomaize starch. Enzymatic hydrolysis was performed using excessBacillus licheniformis α-amylase andAspergillus niger glucoamylase at 37°C and 80°C. The degree of degradation was determined by measuring the dissolved carbohydrates and the weight loss of the samples. Biodegradation was also determined by incubating the samples in a compost environment and measuring the weight loss after composting. The results indicated that the enzymatic method is a rapid means of obtaining preliminary information about the biodegradability of starch-based materials. Other methods are needed to investigate more accurately the extent of biodegradability, especially in the case of complex materials in which starch is blended with other polymers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02067790
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    Biodegradation of starch-poly(β-hydroxybutyrate-co-valerate) composites in municipal activated sludge (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 205-213 
    Details
    ISSN: 1572-8900
    Keywords: Starch ; poly(β′-hydroxybutyrate-co-β-hydroxyvalerate) ; poly(hydroxyalkanoates) ; plastic ; blends ; composite ; biodegradation ; activated sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Injection-molded composites were prepared by blending PHBV5 with native cornstarch (30% and 50%) and with cornstarch precoated with PEO as a binding agent. These composites were evaluated for their biodegradability in municipal activated sludge by measuring changes in their physical and chemical properties over a period of 35 days. All composites lost weight, ranging from 45 to 78% within 35 days. Interestingly, the extent and rate of weight loss were quite similar in PHBV composites with no starch, with 30% starch, and with 50% starch. Weight loss was slowest in PHBV blends prepared with PEO-coated starch. For all samples, the weight loss was accompanied by a rapid deterioration in tensile strength and percentage elongation. The deterioration of these mechanical properties exhibited a relative rate of PHBV〉starch-PHBV〉PEO-coated starch-PHBV. Changes in starch/PHBV composition after biodegradation were quantified by FTIR spectroscopy. Increasing the starch content resulted in more extensive starch degradation, while the PHBV content in the blends became less susceptible to hydrolytic enzymes.
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    URL: http://dx.doi.org/10.1007/BF02068675
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  • 89
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    Composting of miscible cellulose acetate propionate-aliphatic polyester blends (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 1-11 
    Details
    ISSN: 1572-8900
    Keywords: Cellulose ester ; aliphatic polyester ; composting ; biodegradation ; blends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A series of miscible blends consisting of cellulose acetate propionate (CAP) and poly(ethylene glutarate) (PEG) or poly(tetramethylene glutarate) (PTG) were evaluated in a static bench-scale simulated municipal compost environment. Samples were removed from the compost at different intervals, and the weight loss was determined before evaluation by gel permeation chromatography, scanning electron microscopy, and1H NMR. The type of polyester (PEG versus PTG) in the blend made no difference in composting rates. At fixed CAP degree of substitution (DS), when the content of polyester in the blend was increased, the rate of composting and the weight loss due to composting increased. When the CAP was highly substituted, little degradation was observed within 30 days and almost all of the weight loss was ascribed to loss of polyester. Although the polyester was still observed to degrade faster, when the CAP DS was below approximately 2.0, both components are observed to degrade. The data suggests that initial degradation of the polyester is by chemical hydrolysis and the rate of this hydrolysis is very dependent upon the temperature profile of the compost and upon the DS of the CAP.
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    URL: http://dx.doi.org/10.1007/BF02067788
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  • 90
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    Novel synthesis blends between bacterial polyesters and acrylic rubber: A study on enzymatic biodegradation (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 49-60 
    Details
    ISSN: 1572-8900
    Keywords: PHBV ; polyacrylate ; reactive blending ; biodegradation ; properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The biodegradability of a multicomponent system based on biotechnological occurring polyester (poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV)) with inclusion of acrylate elastomer (polybutylacrylate) (PBA) was investigated. A bacterium which produced extracellular enzymes that degrades PHBV even when blended with PBA was isolated and tentatively designated asAureobacterium saperdae. It was observed, by morphological investigation, that, while the bacterial degradation was permitted for PBA content of 20% by weight, it was inhibited for PBA content of 30%, owing to the occurrence of a rubbery layer that prevents to the bacteria an easy accessibility in the PHBV-rich regions. In fact, owing the bacterial growth, only PHBV was metabolized, whereas no degradation of PBA was detected for blend samples. It was confirmed that the degradation proceeded via surface erosion of PHBV also in the blends. Finally, mechanical tests on PHBV/PBA specimens as a function of degradation extent have shown different behavior of the blends at different the PBA content. Thermal analysis of blends and PHBV has been reported, too
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    URL: http://dx.doi.org/10.1007/BF02067793
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    Confirmation of colonization of degrading bacterium strain SC-17 on poly(3-hydroxybutyrate) cast film (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 187-197 
    Details
    ISSN: 1572-8900
    Keywords: Poly(3-hydroxybutyrate) ; film ; biodegradation ; microbial degradation ; colonization ; colonization kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract To clarify the mechanism of microbial degradation owing to colonization ofPseudomonas sp. strain SC-17 on a poly(3-hydroxybutyrate) (PHB) cast film surface, morphological and spectroscopic analyses of the degraded film were investigated and colonization kinetics on the films is discussed. By spectroscopic analysis of unique hemispherical degradation marks, cells of strain SC-17 adhering to the marks' surface were confirmed. To account for the hemispherical hole formation and their linear enlargement with culture time, a three-dimensional colony growth model toward the interior of the film was developed. The model explained the hemispherical hole formation well. It was concluded that the hemispherical holes resulted from the colonization of strain SC-17 on the film surfaces. It was further determined that the microbial degradation by strain SC-17 is initiated from small pits formed on the PHB film surface.
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    URL: http://dx.doi.org/10.1007/BF02068673
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    Catabolic characteristics of biphenyl-utilizing isolates which cometabolize PCBs (1995)
    Springer
    Biodegradation 6 (1995), S. 75-82 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; chloroalkanoic acids ; chlorobenzoate ; dioxin ; dehalogenation ; polychlorinated biphenyls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract As there are at least three types of bacteria involved in the aerobic mineralization of polychlorinated biphenyls (PCBs), this study was undertaken to determine what catabolic features are lacking in biphenyl-degraders and to determine if chlorobenzoate- and chloroacetate-utilizing bacteria are as indigenous to soil as biphenyl-degraders. Bacteria were tested for their ability to utilize chlorinated acids and to cometabolize Aroclor 1254 and dibenzo-p-dioxane (dioxin). The broad and variable substrate specificity of the biphenyl dioxygenase among strains was noted by the range of 〈1 to 53% cometabolism of total PCB congeners and by the oxidation of dioxin, which was not a growth substrate. Growth on chloroalkanoic acids was more frequent with 2-chloropropionate (87% of all strains), 3-chloropropionate (72%), 4-chlorobutyrate (66%), and less frequent (28%) withtrans-3-chlorocrotonate. However, only one strain,Pseudomonas fluorescens K3, could utilize chloroacetate. No biphenyl-utilizers grew on 2- or 4-chlorobenzoate, and only five strains grew on 3-chlorobenzoate. Acetate and benzoate-utilizers were found in all three soils tested at levels near 106/g, whereas chloroacetate- or chlorobenzoate-utilizers were not detected. The inability of biphenyl-degraders to dehalogenate the products of PCB cometabolism is clearly unrelated to metabolism of saturated chloroaliphatic acids, with the notable exception of chloroacetate, since most strains grew on them. Thus, the inability to utilize chloroacetate, a central intermediate in the meta fission pathway, may be relevant to the incomplete catabolism of PCBs by biphenyl-utilizers.
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    URL: http://dx.doi.org/10.1007/BF00702302
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    Metabolism of halohydroquinones inRhodococcus chlorophenolicus PCP-1 (1995)
    Springer
    Biodegradation 6 (1995), S. 119-126 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; aromatic dechlorination ; reductive dechlorination ; hydrolytic dechlorination ; pentachlorophenol ; ring cleavage ; chlorohydroquinone ; bromohydroquinone ; fluorohydroquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The actinomyceteRhodococcus chlorophenolicus PCP-1 metabolises pentachlorophenol into ultimate inorganic end products via tetrachloro-p-hydroquinone. This intermediate was further dehalogenated in the cytoplasm requiring reductant in the cell free system. Tetrafluoro-p-hydroquinone and tetrabromo-p-hydroquinone were also dehalogenated. Chlorophenol analogs, thiol blocking agents and molecular oxygen inhibited the activity. The dehalogenating reactions led to 1,2,4-trihydroxybenzene, which was further metabolized into maleic acid.
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    URL: http://dx.doi.org/10.1007/BF00695342
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    Removal of toluene in waste gases using a biological trickling filter (1995)
    Springer
    Biodegradation 6 (1995), S. 109-118 
    Details
    ISSN: 1572-9729
    Keywords: analytical model ; biodegradation ; gas/liquid mass transfer ; kinetics ; surface removal rate ; toluene ; trickling filter ; waste gas treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The removal of toluene from waste gas was studied in a trickling biofilter. A high level of water recirculation (4.7 m h−1) was maintained in order to keep the liquid phase concentration constant and to achieve a high degree of wetting. For loads in the range from 6 to 150 g m−3 h−1 the maximum volumetric removal rate (elimination capacity) was 35±10 g m−3 h−1, corresponding to a zero order removal rate of 0.11±0.03 g m−2 h−1 per unit of nominal surface area. The surface removal was zero order above the liquid phase concentrations of approximately 1.0 g m−3, corresponding to inlet gas concentrations above 0.7–0.8 g m−3. Below this concentration the surface removal was roughly of first order. The magnitude of the first order surface removal rate constant, k1A , was estimated to be 0.08–0.27 m h−1 (k1A a=24–86 h−1). Near-equilibrium conditions existed in the gas effluent, so mass transfer from gas to liquid was obviously relatively fast compared to the biological degradation. An analytical model based on a constant liquid phase concentration through the trickling filter column predicts the effluent gas concentration and the liquid phase concentration for a first and a zero order surface removal. The experimental results were in reasonable agreement with a very simple model valid for conditions with an overall removal governed by the biological degradation and independent of the gas/liquid mass transfer. The overall liquid mass transfer coefficient, KLa, was found to be a factor 6 higher in the system with biofilm compared to the system without. The difference may be explained by: 1. Difference in the wetting of the packing material, 2. Mass transfer occurring directly from the gas phase to the biofilm, and 3. Enlarged contact area between the gas phase and the biofilm due to a rough biofilm surface.
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    URL: http://dx.doi.org/10.1007/BF00695341
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    Effect of carbon:nitrogen ratio on kinetics of phenol biodegradation byAcinetobacter johnsonii in saturated sand (1995)
    Springer
    Biodegradation 6 (1995), S. 283-293 
    Details
    ISSN: 1572-9729
    Keywords: Acinetobacter ; biodegradation ; carbon nitrogen ratio ; kinetics ; phenol ; sand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In polluted soil or ground water, inorganic nutrients such as nitrogen may be limiting, so that Monod kinetics for carbon limitation may not describe microbial growth and contaminant biodegradation rates. To test this hypothesis we measured14CO2 evolved by a pure culture ofAcinetobacter johnsonii degrading 120 µg14C-phenol per ml in saturated sand with molar carbon:nitrogen (CN) ratios ranging from 1.5 to 560. We fit kinetics models to the data using non-linear least squares regression. Phenol disappearance and population growth were also measured at CN1.5 and CN560. After a 5- to 10-hour lag period, most of the14CO2 evolution curves at all CN ratios displayed a sigmoidal shape, suggesting that the microbial populations grew. As CN ratio increased, the initial rate of14CO2 evolution decreased. Cell growth and phenol consumption occurred at both CN1.5 and CN560, and showed the same trends as the14CO2 data. A kinetics model assuming population growth limited by a single substrate best fit the14CO2 evolution data for CN1.5. At intermediate to high CN ratios, the data were best fit by a model originally formulated to describe no-growth metabolism of one substrate coupled with microbial growth on a second substrate. We suggest that this dual-substrate model describes linear growth on phenol while nitrogen is available and first-order metabolism of phenol without growth after nitrogen is depleted.
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    URL: http://dx.doi.org/10.1007/BF00695259
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    Biodegradation of the nitroaromatic herbicide dinoseb (2-sec-butyl-4,6-dinitrophenol) under reducing conditions (1995)
    Springer
    Biodegradation 6 (1995), S. 329-337 
    Details
    ISSN: 1572-9729
    Keywords: nitroaromatics ; dinoseb ; anaerobic degradation ; biodegradation ; herbicide ; quinones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degradation pathway for dinoseb (2-sec-butyl-4,6-dinitrophenol) under reducing conditions was investigated. Cultures were inoculated with a dinoseb-degrading anaerobic enrichment culture used in field studies. Biotransformation intermediates were extracted with ethyl acetate and analyzed by high pressure liquid chromatography, gas chromatography, and mass spectrometry. Dinoseb degradation involves reduction of the nitro groups to amino groups followed by replacement with hydroxyl groups. Depending on the pH and redox potential in the culture, these intermediates may exist as quinones or hydroquinones.
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    URL: http://dx.doi.org/10.1007/BF00695263
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    Effects of organic compounds on the degradation ofp-nitrophenol in lake and industrial wastewater by inoculated bacteria (1995)
    Springer
    Biodegradation 6 (1995), S. 275-281 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; p-nitrophenol ; Pseudomonas ; Corynebacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Many microorganisms fail to degrade pollutants when introduced in different natural environments. This is a problem in selecting inocula for bioremediation of polluted sites. Thus, a study was conducted to determine the success of four inoculants to degradep-nitrophenol (PNP) in lake and industrial wastewater and the effects of organic compounds on the degradation of high and low concentrations of PNP in these environments.Corynebacterium strain Z4 when inoculated into the lake and wastewater samples containing 20 µg/ml of PNP degraded 90% of PNP in one day. Addition of 100 µg/ml of glucose as a second substrate did not enhance the degradation of PNP and the bacterium utilized the two substrates simultaneously. Glucose used at the same concentration (100 µg/ml), inhibited degradation of 20 µg of PNP in wastewater byPseudomonas strain MS. However, glucose increased the extent of degradation of PNP byPseudomonas strain GR. Phenol also enhanced the degradation of PNP in wastewater byPseudomonas strain GR, but had no effect on the degradation of PNP byCorynebacterium strain Z4. Addition of 100 µg/ml of glucose as a second substrate into the lake water samples containing low concentration of PNP (26 ng/ml) enhanced the degradation of PNP and the growth ofCorynebacterium strain Z4. In the presence of glucose, it grew from 2×104 to 4×104 cells/ml in 3 days and degraded 70% of PNP as compared to samples without glucose in which the bacterium declined in cell number from 2×104 to 8×103 cells/ml and degraded only 30% PNP. The results suggest that in inoculation to enhance biodegradation, depending on the inoculant, second organic substrate many play an important role in controlling the rate and extent of biodegradation of organic compounds.
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    URL: http://dx.doi.org/10.1007/BF00695258
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    Physiological properties and substrate specificity of a pentachlorophenol-degradingPseudomonas species (1994)
    Springer
    Biodegradation 5 (1994), S. 47-54 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; dechlorination ; pentachlorophenol ; Pseudomonas sp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A bacterial strain capable of utilizing pentachlorophenol (PCP) as sole source of carbon and energy for growth was isolated from enrichment cultures containing 100 mg/l PCP in a mineral salts medium inoculated with contaminated soil from a lumber treatment waste site. The isolate, designated strain SR3, was identified as a species ofPseudomonas by virtue of its physiological and biochemical characteristics. Mineralization of PCP byPseudomonas sp. strain SR3 was demonstrated by loss of detectable PCP from growth medium, stoichiometry of chloride release (5 equivalents of chloride per mole of PCP), and formation of biomass consistent with the concentration of PCP mineralized. PCP-induced cells of strain SR3 showed elevated rates of oxygen consumption in the presence of PCP, and with different chlorinated phenols, with complete degradation of 2,3,5,6-, 2,3,6-, 2,4,6-, 2,4-, and 2,6-chloro-substituted phenols. Concentrations of PCP up to 175 mg/liter supported growth of this organism, but maximal rates of PCP removal were observed at a PCP concentration of 100 mg/liter. Based on its degradative properties,Pseudomonas sp. strain SR3 appears to have utility in bioremediation of soil and water contaminated with PCP.
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    URL: http://dx.doi.org/10.1007/BF00695213
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    Biotransformation of quinoline and methylquinolines in anoxic freshwater sediment (1994)
    Springer
    Biodegradation 5 (1994), S. 113-120 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; quinoline ; methylquinolines ; anaerobic biotransformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quinoline (Q) and some isomers of methylquinoline (MQ) were transformed to hydroxylated products in freshwater sediment slurries incubated under methanogenic conditions at 25 °C. Methylquinoline transformation was not affected by a methyl group on the C-3 or C-4 carbon atom of the pyridine ring; 2-MQ, however, was not transformed. All isomers of dimethylquinoline (DMQ) tested (2,4-, 2,6-, 2,7-, and 2,8-DMQ) with a methyl group at the number 2 carbon also persisted in sediments after anaerobic incubation for one year at 25 °C. In most experiments, quinoline initially was transformed to 2-hydroxyquinoline (2-OH-Q), which was further metabolized to unidentified products. A second product, 4-CH3-2-OH-Q, was detected in some experiments. This product accumulated and was not further transformed. 6-, 7-, and 8-Methylquinoline (6-, 7-, 8-MQ) were hydroxylated to form the respective 2-OH-MQ products. These hydroxylated products accumulated and were not further transformed. Hydroxylation of Q and 6-, 7- and 8-MQ at the 2-carbon position was confirmed by GC/FTIR and GC/MS analyses. The transformations of Q and MQs were pH dependent with an optimal pH of 7–8. The results of this study suggest that two pathways may exist for the anaerobic transformation of quinoline; one pathway leads to the formation of a hydroxylated intermediate and the other to a methylated and hydroxylated intermediate. In addition, our results suggest that a methyl substituent on the number 2 carbon inhibits the anaerobic transformation of quinoline derivatives.
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    URL: http://dx.doi.org/10.1007/BF00700636
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    Genetics and biochemistry of 1,2-dichloroethane degradation (1994)
    Springer
    Biodegradation 5 (1994), S. 249-257 
    Details
    ISSN: 1572-9729
    Keywords: chlorinated hydrocarbons ; biodegradation ; 1,2-dichloroethane ; alkanes ; Xanthobacter ; dehalogenase ; adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dichloroethane (1,2-DCE) is a synthetic compound that is not known to be formed naturally. Nevertheless, several pure microbial cultures are able to use it as a sole carbon source for growth. Degradation of 1,2-DCE proceeds via 2-chloroethanol, chloroacetaldehyde and chloroacetate to glycolate. The genes encoding the enzymes responsible for the conversion of 1,2-DCE to glycolic acid have been isolated. The haloalkane dehalogenase and an aldehyde dehydrogenase are plasmid encoded. Two other enzymes, the alcohol dehydrogenase and the haloacid dehalogenase, are chromosomally encoded. Sequence analysis indicates that the haloacid dehalogenase belongs to the L-specific 2-chloroproprionic acid dehalogenases. From the three-dimensional structure and sequence similarities, the haloalkane dehalogenase appears to be a member of the α/β hydrolase fold hydrolytic enzymes, of which several are involved in the degradation of aromatic and aliphatic xenobiotic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696463
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