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  • 1
    Electronic Resource
    Electronic Resource
    Anaerobic biotransformations of pollutant chemicals in aquifers (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 179-194 
    Details
    ISSN: 1476-5535
    Keywords: Aquifer ; Biodegradation, anaerobic ; Pollutant ; Groundwater ; Methanogenesis ; Sulfate-reduction ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Anaerobic microbial communities sampled from either a methanogenic or sulfate-reducing aquifer site have been tested for their ability to degrade a variety of groundwater pollutants, including halogenated aromatic compounds, simple alkyl phenols and tetrachloroethylene. The haloaromatic chemicals were biodegraded in methanogenic incubations but not under sulfate-reducing conditions. The primary degradative event was typically the reductive removal of the aryl halides. Complete dehalogenation of the aromatic moiety was required before substrate mineralization was observed. The lack of dehalogenation activity in sulfatereducing incubations was due, at least in part, to the high levels of sulfate rather than a lack of metabolic potential. In contrast, the degradation of cresol isomers occurred in both types of incubations but proved faster under sulfate-reducing conditions. The requisite microorganisms were enriched and the degradation pathway forp-cresol under the latter conditions involved the anaerobic oxidation of the aryl methyl group. Tetrachloroethylene was also degraded by reductive dehalogenation but under both incubation conditions. The initial conversion of this substrate to trichloroethylene was generally faster under methanogenic conditions. However, the transformation pathway slowed when dichloroethylene was produced and only trace concentrations of vinyl chloride were detected. These results illustrate that pollutant compounds can be biodegraded under anoxic conditions and a knowledge of the predominant ecological conditions is essential for accurate predictions of the transport and fate of such materials in aquifers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569525
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  • 2
    Electronic Resource
    Electronic Resource
    The anaerobic biodegradation ofo-, m- andp-cresol by sulfate-reducing bacterial enrichment cultures obtained from a shallow anoxic aquifer (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 255-266 
    Details
    ISSN: 1476-5535
    Keywords: Sulfate-reduction ; Anaerobic biodegradation ; Ground water ; Bacterial enrichment ; Phenol ; Cresol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Sulfate-reducing bacterial enrichments were obtained from a shallow anoxic aquifer for their ability to metabolize eithero-, m-, orp-cresol. GC/MS and simultaneous adaptation experiments suggested that the anaerobic decomposition ofp-cresol proceeds by the initial oxidation of the aryl methyl group to formp-hydroxybenzoic acid. This intermediate was then converted to benzoic acid. Benzoic acid and a hydroxybenzaldehyde were also found in spent culture fluids from ano-cresol-degrading enrichment culture. This result, in addition to others, suggested thato-cresol may also be anaerobically degraded by the oxidation of the methyl substituent. An alternate pathway for anaerobicm-cresol decomposition might exist. Enrichment cultures obtained with eitherp- oro-cresol degraded both of these substrates but notm-cresol. In contrast, am-cresol enrichment culture did not metabolize theortho orpara isomers. Anaerobic biodegradation in all enrichment cultures was inhibited by molybdate and oxygen, and was dependent on the presence of sulfate as a terminal electron acceptor. The stoichiometry of sulfate-reduction and substrate depletion by the various enrichment cultures indicated that the parent cresol isomers were completely mineralized. This result was confirmed by the conversion of14C-labeledp-cresol to14CO2. These results help clarify the fate of alkylated aromatic chemicals in anoxic aquifers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01577348
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  • 3
    Electronic Resource
    Electronic Resource
    Environmental factors influencing methanogenesis in a shallow anoxic aquifer: a field and laboratory study (1990)
    Springer
    Journal of industrial microbiology and biotechnology 5 (1990), S. 45-57 
    Details
    ISSN: 1476-5535
    Keywords: Methane production ; pH ; Temperature ; Sulfate ; Ground water ; Anaerobic metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The environmental factors influencing methanogenesis in a shallow anoxic aquifer were probed in a combined field and laboratory study. Field data collected over a year revealed that ‘in situ’ rates of methane production were depressed in winter and elevated in summer. Over the same period, ground water pH values ranged from 6.0 to 7.8 while temperatures varied from 7–22°C. ‘In situ’ methanogenesis was severely inhibited at temperatures 〈 13°C or by pH values 〈 7. The influence of these factors on microbial methane formation from both endogenous and exogenous substrates were tested in aquifer slurries adjusted to pH 5–9 and incubated at temperatures ranging from 5–45°C. Temperature optima for methane production from endogenous substrates varied as a function of pH, but the pH optimum was 8 at all temperatures. Optimal conditions for acetoclastic methanogenesis were found at pH 8 and 35°C. An analysis of variance revealed that pH, temperature, and a pH-temperature interaction are all significant variables influencing aquifer methanogenesis. In addition transient sulfate accumulations were also found to limit methane production in some areas. A comparison of field and laboratory methane production patterns suggest that pH, temperature, and sulfate accumultations are important, but not the only environmental variables influencing the mineralization of organic matter in shallow aquifers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569605
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  • 4
    Electronic Resource
    Electronic Resource
    Role of electron-donating cosubstrates in the anaerobic biotransformation of chlorophenoxyacetates to chlorophenols by a bacterial consortium enriched on phenoxyacetate (1993)
    Springer
    Biodegradation 4 (1993), S. 51-57 
    Details
    ISSN: 1572-9729
    Keywords: 2,4,5-T ; ether cleavage ; anaerobic biodegradation ; aromatic 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 bacterial consortium that anaerobically mineralized phenoxyacetate, with transient production of phenol as an intermediate, was obtained from a methanogenic aquifer site near the Norman, OK municipal landfill. This consortium was able to convert the eight halogenated chlorophenoxyacetates tested to the corresponding chlorophenols. The chlorophenols were not subsequently metabolized. The addition of reduced substrates increased the rate of degradation of all chlorophenoxyacetates, with 78% of mono- and di-chlorinated substrates being transformed to chlorophenols in butyrate-amended cultures, compared to less than 37% transformed in unsupplemented cultures. Butyrate increased the transformation of 2,4,5-trichlorophenoxyacetate from 10% to 20%. An experiment evaluating the effects of several compounds on the side-chain cleavage reaction of 3-chlorophenoxyacetate showed that addition of compounds with readily act as hydrogen donors (butyrate, crotonate, ethanol, propionate, and hydrogen) resulted in 2 to 5 times the amount of 3-chlorophenoxyacetate transformed compared to controls with no amendment, formate had a slight stimulatory effect, and acetate and methanol had no effect. Butyrate addition also increased the rate of phenoxyacetate degradation, resulting in transient phenol accumulation not observed in butyrate-unamended controls. These results support the hypothesis that the side-chain cleavage of phenoxyacetate is a reductive process that is stimulated by the oxidation of reduced cosubstrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00701454
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  • 5
    Electronic Resource
    Electronic Resource
    Desulfomonile tiedjei gen. nov. and sp. nov., a novel anaerobic, dehalogenating, sulfate-reducing bacterium (1990)
    Springer
    Archives of microbiology 154 (1990), S. 23-30 
    Details
    ISSN: 1432-072X
    Keywords: Desulfomonile ; Sulfate-reducing bacteria ; Dehalogenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An anaerobic, dehalogenating, sulfate-reducing bacterium, strain DCB-1, is described and nutritionally characterized. The bacterium is a Gram-negative, nonmotile, non-sporeforming large rod with an unusual morphological feature which resembles a collar. The microorganism reductively dehalogenates meta substituted halobenzoates and also reduces sulfate, sulfite and thiosulfate as electron acceptors. The bacterium requires nicotinamide, 1,4-naphthoquinone and thiamine for optimal growth in a defined medium. The microorganism can grow autotrophically on H2:CO2 with sulfate or thiosulfate as terminal electron acceptors. It can also grow heterotrophically with pyruvate, several methoxybenzoates, formate plus sulfate or benzoate plus sulfate. It ferments pyruvate to acetate and lactate in the absence of other electron acceptors. The bacterium is inhibited by MoO inf4 sup2- or SeO inf4 sup2- as well as tetracycline, chloramphenicol, kanamycin or streptomycin. Cytochrome c3 and desulfoviridin have been purified from cells grown in defined medium. 16S rRNA sequence analysis indicates the organism is a new genus of sulfate-reducing bacteria in the delta subdivision of the class Proteobacteria. We propose that the strain be named Desulfomonile tiedjei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249173
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  • 6
    Electronic Resource
    Electronic Resource
    Microbial ecology of a shallow unconfined ground water aquifer polluted by municipal landfill leachate (1987)
    Springer
    Microbial ecology 14 (1987), S. 39-54 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The microflora of a shallow anoxic aquifer underlying a municipal landfill in Oklahoma was characterized by direct light microscopy, most probable number determinations of sulfate reducers and methanogens, and measurements of methanogenesis in aquifer samples containing either endogenous or exogenous electron donors and various sulfate concentrations. Acridine orange direct counts of bacteria did not vary significantly with time or between 2 major sampling areas (1.70±0.16×107 to 11.2±2.1×107 cells/gdw). One site (B) was high in organic matter and low in sulfate, and methanogens generally outnumbered sulfate-reducers at most times of the year, whereas the opposite was true for another site (A). Greater than 75% of the theoretical amount of methane was detected within 7 weeks in both site A and B aquifer slurries amended with noncompetitive electron donors like methanol and trimethylamine. However, only site B slurries efficiently converted competitive donors like acetate, H2, and formate to the expected amount of methane. A mapping of sulfate and methane levels indicated that site A is relatively localized. These results suggest that the predominant flow of carbon and energy is through methanogenesis at aquifer site B whereas sulfate reduction predominated at site A. However, both methanogens and sulfate reducers could be isolated from either site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02011569
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  • 7
    Electronic Resource
    Electronic Resource
    Anaerobic biodegradation of methyl esters byAcetobacterium woodii andEubacterium limosum (1994)
    Springer
    Journal of industrial microbiology and biotechnology 13 (1994), S. 321-327 
    Details
    ISSN: 1476-5535
    Keywords: Methyl esters ; Methoxylated compounds ; Anaerobic biodegradation ; Demethoxylation ; O-Demethylation ; Acetobacterium woodii ; Eubacterium limosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The ability ofAcetobacterium woodii andEubacterium limosum to degrade methyl esters of acetate, propionate, butyrate, and isobutyrate was examined under growing and resting-cell conditions. Both bacteria hydrolyzed the esters to the corresponding carboxylates and methanol under either condition. Methanol was further oxidized to formate under growing but not resting conditions. Unlike the metabolism of phenylmethylethers, no H2 requirement was evident for ester biotransformation. The hydrolysis of methyl carboxylates is thermodynamically favorable under standard conditions and the mixotrophic metabolism of ester/CO2 allowed for bacterial growth. These results suggest that the degradation of methyl carboxylates may be a heretofore unrecognized nutritional option for acetogenic bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569735
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  • 8
    Electronic Resource
    Electronic Resource
    H2 as an energy source for mixotrophic acetogenesis from the reduction of CO2 and syringate by Acetobacterium woodii and Eubacterium limosum (1995)
    Springer
    Current microbiology 31 (1995), S. 245-250 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Acetobacterium woodii and Eubacterium limosum were grown in a defined medium or suspended in buffer containing syringate as the sole organic carbon source to test whether H2 would support acetogenesis from a phenylmethylether and CO2. When growing and resting cell preparations were incubated under various headspace gas compositions, consistent O-demethylation activity and growth were observed on syringate-CO2 when H2 served as the sole energy source. However, the dependency for H2 was relieved by addition of yeast extract. A hypothetical scheme representing hydrogenolytic (reductive) O-demethylation and mixotrophic acetogenesis is proposed in light of these results and other literature observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298382
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  • 9
    Electronic Resource
    Electronic Resource
    Carboxylation and mineralization ofm-cresol by a sulfate-reducing bacterial enrichment (1993)
    Springer
    Current microbiology 26 (1993), S. 327-332 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An enrichment culture that anaerobically degradedm-cresol under sulfate-reducing conditions was obtained from an anoxic aquifer.m-Cresol removal by the culture was greatest when sulfate or thiosulfate served as electron acceptors; sulfite, nitrate, and CO2 were poor substitutes for sulfate. A14C-labeled carboxylated intermediate was detected when the culture was given14C-labeled bicarbonate and nonlabeledm-cresol or nonlabeled bicarbonate and14C-labeledm-cresol. Metabolism of the carboxylated intermediate yielded14C-acetate, which was eventually converted to14CO2. Trace quantities of methylbenzoic acid were also detected as a putativem-cresol intermediate. The importance of this dehydroxylated intermediate in the anaerobic degradation ofm-cresol is unclear, since an amendment of 2-methylbenzoic acid was not degraded by the culture. The stoichiometry of electron acceptor consumption and carbon mass balances confirm thatm-cresol was mineralized by the culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01576264
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  • 10
    Electronic Resource
    Electronic Resource
    The metabolism of the ground water contaminant 2-hydroxybiphenyl under sulfate-reducing conditions (1991)
    Springer
    Current microbiology 22 (1991), S. 69-72 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The metabolic fate of 2-hydroxybiphenyl under different anaerobic conditions was tested with sediment slurries and enrichment cultures obtained from a shallow anoxic aquifer. 2-Hydroxybiphenyl was depleted in aquifer slurries over the course of incubation, but substrate loss in methanogenic slurries was not significantly different from either filter-sterilized or autoclaved controls. In contrast, the rate of substrate removal was significantly higher in non-sterile, sulfate-reducing aquifer slurries relative to abiotic control incubations. A 2-hydroxybiphenyl-degrading enrichment was established that was inhibited by molybdate but not by bromoethane-sulfonic acid. For every mole of substrate consumed by the bacterial consortium, 6.1±0.2 moles of sulfate were depleted from the enrichment medium. This represents about 87% of the theoretical amount of sulfate consumed and suggests that the 2-hydroxybiphenyl was largely mineralized. Oxygen, nitrate, or carbon dioxide could not replace sulfate as a terminal electron acceptor for the enrichment. Other hydroxybiphenyl isomers were not metabolized by these cultures. This study shows that aromatic substrates with multiple ring systems can undergo biotransformation by anaerobic microorganisms under some ecological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02106216
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