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  • Articles  (15)
  • ethanol  (15)
  • 2020-2024
  • 1990-1994  (15)
  • 1985-1989
  • 1950-1954
  • 1994  (9)
  • 1993  (6)
  • Process Engineering, Biotechnology, Nutrition Technology  (15)
  • Sociology
  • 1
    Electronic Resource
    Electronic Resource
    Ethanolic dehydration and its effect on membrane-bound enzymes of Chlorogloeopsis fritschii and Chlorella pyrenoidosa (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 187-190 
    Details
    ISSN: 1573-0972
    Keywords: Chlorella pyrenoidosa ; Chlorogloeopsis fritschii ; dehydration ; ethanol ; glutamine synthetase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Ethanolic dehydration (20% to 70%) of the thylakoid membranes of Chlorogloeopsis fritschii resulted in an 8% to 58% loss of glutamine synthetase activity. In Chlorella pyrenoidosa, hydroxypyruvate reductase and fumarase, marker enzymes of the peroxisomes and mitochondria, respectively, diffused from the organelles on dehydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00360884
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  • 2
    Electronic Resource
    Electronic Resource
    Pervaporative butanol fermentation by Clostridium acetobutylicum B18 (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 978-986 
    Details
    ISSN: 0006-3592
    Keywords: butanol ; fermentation ; Clostridium acetobutylicum ; acetone ; ethanol ; pervaporation ; fed batch ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extractive acetone-butanol-ethanol (ABE) fermentation was carried out successfully using pervaporation and a low-acid-producing Clostridium acetobutylicum B18. A pervaporation module with 0.17 m2 of surface area was made of silicone membrane of 240 μm thickness. Pervaporation experiments using make-up solutions showed that butanol and acetone fluxes increased linearly with their concentrations in the aqueous phase. Fickian diffusion coefficients were constants for fixed air flow rates, and increased at higher sweep air flow rates. During batch and fed-batch fermentations, pervaporation at an air flow rate of 8 L/min removed butanol and acetone efficiently. Butanol concentration was maintained below 4.5 g/L even though Clostridium acetobutylicum B18 produced butanol steadily. Pervaporation could not remove organic acids efficiently, but organic acids did not accumulate because strain B18 produced little organic acid and recycled added organic acids efficiently. With pervaporation, glucose consumption rate increased compared to without pervaporation, and up to 160 g/L of glucose was consumed during 80 h. Cell growth was not inhibited by possible salt accumulation or oxygen diffusion through the silicone tubing. The culture volume was maintained relatively constant during fed-batch operation because of an offsetting effect of water and product removal by pervaporation and addition of nutrient supplements. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260431011
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  • 3
    Electronic Resource
    Electronic Resource
    Ethanol production from nonsterilized carob pod extract by free and immobilized Saccharomyces cerevisiae cells using fed-batch culture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 189-194 
    Details
    ISSN: 0006-3592
    Keywords: ethanol ; Saccharomyces cerevisiae ; carob pod ; fed-batch culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of ethanol from carob pod extract by free and immobilized Saccharomyces cerevisiae cells in batch and fed-batch culture was investigated. Fed-batch culture proved to be a better fermentation system for the production of ethanol than batch culture. In fed-batch culture, both free and immobilized S. cerevisiae cells gave the same maximum concentration (62 g/L) of final ethanol at an initial sugar concentration of 300 g/L and F = 167 mL/h. The maximum ethanol productivity (4.4 g/L h) was obtained with both free and immobilized cells at a substrate concentration of 300 g/L and F = 334 mL/h. In repeated fed-batch culture, immobilized S. cerevisiae cells gave a higher overall ethanol concentration compared with the free cells. The immobilized S. cerevisiae cells in Ca-alginate beads retained their ability to produce ethanol for 10 days. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430302
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  • 4
    Electronic Resource
    Electronic Resource
    Differences in response of Zymomonas mobilis and Saccharomyces cerevisiae to change in extracellular ethanol concentration (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 155-158 
    Details
    ISSN: 0006-3592
    Keywords: Zymomonas ; yeast ; ethanol ; inhibition ; adaptation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In high cell density batch fermentations, Zymomonas mobilis produced 91 g L-1 ethanol in 90 min but culture viability fell significantly. Similar viability losses in rapid fermentations by yeast have recently been shown to be attributable in part to the high rate of change of the extracellular ethanol concentration. However, in simulated rapid fermentations in which ethanol was pumped continuously to low cell density Z. mobilis suspensions, increases in the rate of change of ethanol concentration in the range 21-83 g L-1 h-1 did not lead to accelerated viability losses. The lag phase of Zymomonas cultures exposed to a 30-g L-1 step change in ethanol concentration was much shorter than that of Saccharomyces cerevisiae, providing evidence that the comparative insensitivity of Zymomonas to high rates of change of ethanol concentration is due to its ability to adapt to changes in ethanol concentration more rapidly than yeast. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430208
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  • 5
    Electronic Resource
    Electronic Resource
    A new method for studying microaerobic fermentations. II. An experimental investigation of xylose fermentation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 429-435 
    Details
    ISSN: 0006-3592
    Keywords: dynamic experiments ; ethanol ; xylose ; microaerobic fermentation ; oxygen limitation ; on-line monitoring ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new experimental technique, called oxygen programmed fermentation (OPF), was used to study microbial cultures of the years Pichia stipitis and Candida utilis growing on xylose as carbon and energy source. In the oxygen programmed fermentation, the inlet oxygen mole fraction was continuously changed to scan through a wide range of oxygen uptake rates in a continuous culture. The largest ethanol yields and productivities of P. stipitis were found at oxygen transfer rates below 1.5 mmol L-1 h-1. It was found that the ratio between the culture fluorescence and near-IR absorbance increased at oxygen transfer rates lower than 1.5 mmol L-1 h-1. Small amounts of ethanol were produced also by C. utilis when the oxygen transfer rate was between 0 and 3 mmol L-1 h-1. It is suggested that OPF will form a nice complement to ordinary, microaerobic chemostat experiments, by making the identification of interesting regions of oxygen transfer rates possible in an efficient and time-saving initial experiment. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440405
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  • 6
    Electronic Resource
    Electronic Resource
    Saccharification and fermentation of Sugar Cane bagasse by Klebsiella oxytoca P2 containing chromosomally integrated genes encoding the Zymomonas mobilis ethanol pathway (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 240-247 
    Details
    ISSN: 0006-3592
    Keywords: lignocellulose ; ethanol ; Klebisella oxytoca ; fermentation ; cellulase ; cellulose ; cellobiose ; biomass ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pretreatment of sugar cane bagasse is essential for a simultaneous saccharification and fermentation (SSF) process which uses recombinant Klebsiella oxytoca strain P2 and Genencor Spezyme CE. Strain P2 has been genetically engineered to express Zymomonas mobilis genes encoding the ethanol pathway and retains the native ability to transport and metabolize cellobiose (minimizing the need for extracellular cellobiase). In SSF studies with this organism, both the rate of ethanol production and ethanol yield were limited by saccharification at 10 and 20 filter papaer units (FPU) g-1 acid-treated bagasse. Dilute slurries of biomass were converted to ethanol more efficiently (over 72% of theoretical yield) in simple batch fermentations than slurries containing high solids albeit with the production of lower levels of ethanol. With high solids (i.e., 160 g acid-treated bagasse L-1), a combination of 20 FPU cellulase g-1 bagasse, preincubation under saccharification conditions, and additional grinding (to reduce particle size) were required to produce ca. 40 g ethanol L-1. Alternatively, almost 40 g ethanol L-1 was produced with 10 FPU cellulase g-1 bagasse by incorporating a second saccharification step (no further enzyme addition) followed by a second inoculation and short fermentation. In this way, a theoretical ethanol yield of over 70% was achieved with the production of 20 g ethanol 800 FPU-1 of commercial cellulase. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440213
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  • 7
    Electronic Resource
    Electronic Resource
    Monitoring of ethanol during fermentation of a lignocellulose hydrolysate by on-line microdialysis sampling, column liquid chromatography, and an alcohol biosensor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 322-328 
    Details
    ISSN: 0006-3592
    Keywords: biosensor ; ethanol ; fermentation ; lignocellulose hydrolysate ; liquid chromatography ; microdialysis ; on-line ; sampling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During a 70-h fermentation of a lignocellulose hydrolysate, the ethanol produced was monitored on-line using a microdialysis probe as an in situ sampling device. The dialysate components were then separated in a column liquid chromatographic system and the ethanol was selectively detected by an amperometric alcohol biosensor. The result was compared with two off-line analysis methods: one chromatographic method with refractive index (RI) detection and one enzymatic method based on spectrophotometric detection. The two methods base on enzymes were shown to give lower values than the chromatographic method based on RI detection, which is discussed n terms of selectivity. The investigated on-line setup was found to be a flexible system for monitoring of fermentations, allowing a sampling frequency of at least 12 h-1 and with a delay between sampling and detection of less than 5 min. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440309
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  • 8
    Electronic Resource
    Electronic Resource
    Saccharification, fermentation, and protein recovery from low-temperature AFEX-treated coastal bermudagrass (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1122-1131 
    Details
    ISSN: 0006-3592
    Keywords: cellulase ; protein ; AFEX ; ethanol ; lignocellulose ; HCH-1 model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Coastal bermudagrass was pretreated by a low-temperature ammonia fiber explosion (AFEX) process, which soaked the grass in liquid ammonia and then explosively released the pressure. Saccharifying enzymes were systematically applied to the AFEX-treated grass corresponding to low, medium, and high loadings of cellulase/hemicellulase (from Trichoderma reesei), cellobiase, glucoamylase, and pectinase. Three-day sugar yields linearly correlated with the logarithm of the cellulase loading. Supplemental enzymes (cellobiase, pectinase) caused upward shifts in the lines. The linearity and upward shifts are consistent with the HCH-1 model of cellulose hydrolysis. The hydrolysis sugars were converted to ethanol using yeast (Saccharomyces cerevisiae). The solid residues were treated with proteases to attempt recovery of valuable proteins. The low-temperature AFEX pretreatment was able o nearly double sugar yields. At the highest cellulase loadings (30 IU/g), the best reducing sugar and ethanol yields were 53% and 44% of the maximum potential, respectively. Protein recovery was, at most, 59% © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440914
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of alcohol feeding mode on the biosynthesis of poly (3-hydroxybutyrate-co-3-hyroxyvalerate) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1306-1314 
    Details
    ISSN: 0006-3592
    Keywords: Poly(3-hydroxybutyrate-co-3-hydroxyoxy-valerate) ; ethanol ; propanol ; copolymer ; alcohol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An alcohol utilizing Alcaligenes eutrophus produced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer under phosphate limitation. Fermentation was performed for 42-46 h in a computer-controlled 5-L working volume fed-batch fermentor using ethanol and propanol as carbon sources. The culture experienced phosphate limitation in approximately 19 h. When propanol was used as a sole carbon source, 24 g/L of copolymer with 36.5 mol % of hydroxyvalerate (HV) was produced at a polymer yield of 0.41 g polymer/g alcohol (g/g) and an average polymer production rate of 0.08 g polymer/g residual biomass-h (g/g-h). Two experiments switching alcohol after phosphate exhaustion resulted in better polymer production (g/L), polymer yield (g/g) on alcohol, HV yield (g/g) on propanol, and average polymer production rate (g/g-h) as compared to propanol run without alcohol switching. One switching experiment was from a mixture of 50% ethanol and 50% propanol to 100% propanol and the other experiment was from 100% ethanol to a mixture of 65% ethanol and 35% propanol. Polymer yield for these two experiments was 0.51 g/g and 0.46 g/g, respectively. However, HV mol % in the copolymer for these two runs (30.8 mol % 12.6 mol % respectively) was lower compared to propanol run without alcohol switching (3605 mol %). Direct switch from ethanol to propanol did not support cell growth and polymer production. Polymer production rate and polymer yield changed with time, and the pattern was dependent upon the alcohol feeding mode. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260441106
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  • 10
    Electronic Resource
    Electronic Resource
    Fermentation of starch to ethanol by a co-culture of Saccharomycopsis fibuligera and Saccharomyces cerevisiae (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 338-341 
    Details
    ISSN: 1573-0972
    Keywords: Absence of nutritional supplements ; ethanol ; starch ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Static fermentation of starch to ethanol by a co-culture of Saccharomycopsis fibuligera and Saccharomyces cerevisiae without addition of nutritional supplements was investigated with respect to initial starch concentration, pH of the media and initial dry weight ratio of Sps. fibuligera to Sacc. cerevisiae biomass (I R).Optimal conditions for ethanol production were: starch from 20 to 30 g/l; initial pH values from 5.8 to 6.0; and I R values of 2.0 or 3.0. The highest attained ethanol concentration, 13.7 g/l, represented 88% of the theoretical yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383075
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  • 11
    Electronic Resource
    Electronic Resource
    Genetics and genetic engineering ofZymomonas mobilis (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 17-24 
    Details
    ISSN: 1573-0972
    Keywords: Cloning vectors ; ethanol ; plasmids ; strain improvement ; Zymomonas genetics ; Zymomonas mobilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Present knowledge on the genetics of the ethanologenic anaerobeZymomonas mobilis includes background information on: size, restriction, and to some extent hybridization, analysis of indigenous plasmids; mutagenesis and isolation of a wide variety of auxotrophic, drug resistant and conditional mutants; construction of shuttle cloning vectors able to replicate and express inZ. mobilis; development of gene transfer systems based on conjugal mobilization of plasmids fromEscherichia coli donors toZ. mobilis; expression of heterologous genes inZ. mobilis; cloning and analysis of genes encoding enzymes of the Entner-Doudoroff pathway. Moreover, preliminary data on recombinational repair mechanisms and plasmid stability, which are now available, makeZ. mobilis an attractive model system for molecular genetic research and, furthermore, they contribute towards expansion of the substrate and product range of this industrial microorganism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656509
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  • 12
    Electronic Resource
    Electronic Resource
    Gas phase acetaldehyde production in a continuous bioreactor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 667-673 
    Details
    ISSN: 0006-3592
    Keywords: alcohol oxidase ; acetaldehyde ; ethanol ; continuous bioreactor ; gas phase reaction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The gas phase continuous production of acetaldehyde was studied with particular emphasis on the development of biocatalyst (alcohol oxidase on solid phase support materials) for a fixed bed reactor. Based on the experimental results in a batch bioreactor, the biocatalysts were prepared by immobilization of alcohol oxidase on Amberlite IRA-400, packed into a column, and the continuous acetaldehyde production in the gas phase by alcohol oxidase was performed. The effects of the reaction temperature, flow rates of gaseous stream, and ethanol vapor concentration on the performance of the continuous bioreactor were investigated. © 1993 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420515
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  • 13
    Electronic Resource
    Electronic Resource
    Microbial utilization of levoglucosan in wood pyrolysate as a carbon and energy source (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 538-541 
    Details
    ISSN: 0006-3592
    Keywords: ethanol ; fermentation ; levoglucosan ; lignocellulose ; pyrolysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Waterloo Fast Pyrolysis Process (WFPP) can produce an organic liquid high in levoglucosan (1, 6-anhydro-β-D-glucopyranose) content from suitably pretreated lignocellulosics. A variety of fungi and yeasts were screened for their ability to utilize and ferment this organic liquid. To enhance its fermentability, the pyrolysis tar was posttreated in three different ways: (1) an aqueous extract (lignin removed); (2) activated charcoal treated (lignin and aromatics removed); and (3) acid hydrolysate (lignin and aromatics removed with the levoglucosan hydrolyzed to glucose). Four fungal strains were examined. None grew in the aqueous extract, but all grew equally well in both the activated charcoal treated and the acid hydrolysate, suggesting that the aromatic species were inhibitory to growth. Seven yeast species were examined, two of which did not grow on any of the extracts. Five of the yeast strains grew well on both the aqueous extract as well as the activated charcoal extract. The hydrolysate was optimal in terms of biomass yield and ethanol production. Ethanol yields on the hydrolysate were comparable or better than those on glucose. Ethanol was also produced in the aqueous extract and activated charcoal-treated substrate, but yields were considerably lower than on the hydrolysate or glucose. It is apparent that a wood pyrolysate maximized for levoglucosan can serve as a fermentable substrate, although postpyrolysis clean-up appears necessary. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420419
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  • 14
    Electronic Resource
    Electronic Resource
    Study of the enzymatic hydrolysis of cellulose for production of fuel ethanol by the simultaneous saccharification and fermentation process (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 846-853 
    Details
    ISSN: 0006-3592
    Keywords: enzymatic hydrolysis ; cellulose ; β-glucosidase ; SSF ; ethanol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biochemical conversion of cellulosic biomass to ethanol, a promising alternative fuel, can be carried out efficiently and economically using the simultaneous saccharification and fermentation (SSF) process. The SSF integrates the enzymatic hydrolysis of cellulose to glucose, catalyzed by the synergistic action of cellulase and β-glucosidase, with the fermentative synthesis of ethanol. Because the enzymatic step determines the ethanol. Because the enzymatic step determines the availability of glucose to the ethanologenic fermentation, the kinetic of cellulose hydrolysis by cellulase and β-glucosidase and the susceptibility of the two enzymes to inhibition by hydrolysis and fermentation products are of significant importance to the SSF performance and were investigated under realistic SSF conditions. A previously developed SSF mathematical model was used to conceptualize the depolymerization of cellulose. The model was regressed to the collected data to determine the values of the enzyme parameters and was found to satisfactorily predict the kinetics of cellulose hydrolysis. Cellobiose and glucose were identified as the strongest inhibitors of cellulase and β-glucosidase, respectively. Experimental and modeling results are presented in light of the impact of enzymatic hydrolysis on fuel ethanol production. © 1993 Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260410903
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  • 15
    Electronic Resource
    Electronic Resource
    Bioenergetics and end-product regulation of Clostridium thermosaccharolyticum in response to nutrient limitation (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 873-883 
    Details
    ISSN: 0006-3592
    Keywords: nutrient limitation ; bioenergetics ; thermophiles ; ethanol ; C. thermosaccharolyticum ; ATP ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation of xylose by Clostridium thermosaccharolyticum was studied in batch and continuous culture in which the limiting nutrient was either xylose, phosphate, or ammonia. Transient results obtained in continuous cultures with batch grown inoculum and progressively higher feed substrate concentrations exhibited ethanol selectivities (moles ethanol/moles other products) in excess of 11. The hypothesis that this high ethanol selectivity was a general response to mineral nutrient limitation was tested but could not be supported. Growth and substrate consumption were related by the equation qs(1 - Yxc)GATP = (μ/YATPmax) + m, with qs the specific rate of xylose consumption (moles xylose/hour · g cells), Yxc the carbon based cell yield (g cell carbon/g substrate carbon), GATP the ATP gain (moles ATP produces/mol substrate catabolized), μ the specific growth rate (1/h), YATPmax the ATP-based cell yield (g cells/mol ATP), and m the maintenance coefficient (moles ATP/hour · g cells). YATPmax was found to be 11.6 g cells/mol ATP, and m 9.3 mol ATP/hour · g cells for growth on defined medium. Different responses to nutrient limitation were observed depending on the mode of cultivation. Batch and immobilized cell continuous cultures decreased GATP by initiating production of the secondary metabolites, propanediol, and in some cases, D-lactate; in addition, batch cultures increased the fractional allocation of ATP to maintenance and/or wastage. Nitrogen-limited continuous free-cell cultures maintained a constant cell yield, whereas phosphate-limited continuous free-cell cultures did not. In the case of phosphate limitation, the decreased ATP demand associated with the lowered cell yield was accompanied by an increased rate of ATP consumption for maintenance and/or wastage. Neither nitrogen or phosphorus-limited continuous free-cell cultures exhibited an altered GATP in response to mineral nutrient limitation, and neither produced secondary metabolites. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420712
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