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  • 1
    Electronic Resource
    Electronic Resource
    A kinetic model for substrate and energy consumption of microbial growth under substrate-sufficient conditions (1995)
    s.l. : American Chemical Society
    Biotechnology progress 11 (1995), S. 71-79 
    Details
    ISSN: 1520-6033
    Source: ACS Legacy Archives
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bp00031a010
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  • 2
    Electronic Resource
    Electronic Resource
    Pathway and kinetic analysis of 1,3-propanediol production from glycerol fermentation by Clostridium butyricum (1996)
    Springer
    Bioprocess and biosystems engineering 14 (1996), S. 169-175 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Stoichiometric analysis is applied to continuous glycerol fermentation by Clostridium butyricum to calculate theoretical maximum yields and to predict preferred pathways under different conditions. The upper limits of product concentration and productivity as a function of dilution rate in continuous culture is also predicted from product inhibition kinetic. The theoretical maximum propanediol yield (0.72 mol/mol glycerol) which is calculated for a culture without hydrogen and butyric acid formation agrees well with the experimental maximum value (around 0.71 mol/mol). Comparisons of experimental results (product concentration and productivity) with theoretical calculations and those of the glycerol fermentation by Klebsiella pneumoniae reveal that the production of 1,3-propanediol by C. butyricum is far below the optimum performance available with the present strain. One of the reasons is the relatively high formation of butyric acid under the culture conditions so far applied. The distribution of reducing equivalents to propanediol and hydrogen is also suboptimal. The utilization of the reducing power from pyruvate oxidation for propanediol production is about 60–70% of the theoretical maximum under the present experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01464731
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  • 3
    Electronic Resource
    Electronic Resource
    Reactor comparison and scale-up for the microaerobic production of 2,3-butanediol by Enterobacter aerogenes at constant oxygen transfer rate (1994)
    Springer
    Bioprocess and biosystems engineering 11 (1994), S. 167-175 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Stirred tank (STR), bubble column (BCR) and airlift (ALR) bioreactors of 0.05 and 1.5 m3 total volume were compared for the production of 2,3-butanediol using Enterobacter aerogenes under microaerobic conditions. Batch fermentations were carried out at constant oxygen transfer rate (OTR=35 mmol/lh). At 0.05 m3 scale, the STR reactor achieved much higher biomass and product concentrations than the BCR and ALR reactors. At 1.5 m3 scale, however, exactly the same biomass and product concentrations could be obtained in both STR and ALR reactors. The 1.5 m3 ALR reactor performed also much better than its counterpart at small scale, achieving a productivity 2.4-fold as high as that of the 0.05 m3 BCL and ALR reactors. No differences in performances were observed between BCR and ALR. As compared to STR the tower reactors have a 12 time higher energetic efficiency (referred to product formation) and thus should be the choice for large scale production of 2,3-butanediol. The criterion of constant OTR or constant k L a is not applicable for the scale-up of this oxygen-sensitive culture due to strong influence of reactor hydrodynamics under microaerobic conditions. The effects of mixing and circulation time on growth and metabolism of E. aerogenes were quantitatively studied in scaled-down experiments with continuous culture. For a successful scale-up of this microaerobic culture it is necessary to have an homogeneous oxygen supply over the entire reactor volume. Under conditions of inhomogeneous oxygen supply an optimum liquid circulation time exists which gives a maximum production of 2,3-butanediol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00518739
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  • 4
    Electronic Resource
    Electronic Resource
    Physiological characterization and cultivation strategies of the pentachlorophenol-degrading bacteria Sphingomonas chlorophenolica RA2 and Mycobacterium chlorophenolicum PCP-1 (1998)
    Springer
    Journal of industrial microbiology and biotechnology 21 (1998), S. 315-321 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: pentachlorophenol; biodegradation; growth physiology; cultivation; Mycobacterium chlorophenolicum PCP-1; Sphingomonas chlorophenolica RA2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physiological characteristics of growth and pentachlorophenol degradation of the bacteria Sphingomonas chlorophenolica RA2 and Mycobacterium chlorophenolicum PCP-1 were studied quantitatively in liquid culture under various conditions of pH, temperature, pO2, pCO2 and PCP concentration. Concerning their metabolic properties, RA2 and PCP-1 can be regarded as r-strategist and K-strategist, respectively. RA2 showed a higher activity concerning growth and PCP degradation than PCP-1 under optimum conditions. However, PCP-1 performed better under extreme conditions. Maximum growth rates or RA2 and PCP-1 on glucose were 0.21 h−1 and 0.024 h−1 and maximum PCP degradation rates 315 and 40 μmol (g of dry cells)−1 h−1, respectively. Optimized cultivation for RA2 on a technical scale led to the production of 40 g L−1 of cell dry mass within 55 h. The cultivation strategy including pH-controlled ammonium feeding can be used to effectively produce sufficient biomass of both strains for both research and application as inoculants in soil clean-up.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900595
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  • 5
    Electronic Resource
    Electronic Resource
    Pathway and kinetic analysis of 1,3-propanediol production from glycerol fermentation by Clostridium butyricum (1996)
    Springer
    Bioprocess engineering 14 (1996), S. 169-175 
    Details
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Stoichiometric analysis is applied to continuous glycerol fermentation by Clostridium butyricum to calculate theoretical maximum yields and to predict preferred pathways under different conditions. The upper limits of product concentration and productivity as a function of dilution rate in continuous culture is also predicted from product inhibition kinetic. The theoretical maximum propanediol yield (0.72 mol/mol glycerol) which is calculated for a culture without hydrogen and butyric acid formation agrees well with the experimental maximum value (around 0.71 mol/mol). Comparisons of experimental results (product concentration and productivity) with theoretical calculations and those of the glycerol fermentation by Klebsiella pneumoniae reveal that the production of 1,3-propanediol by C. butyricum is far below the optimum performance available with the present strain. One of the reasons is the relatively high formation of butyric acid under the culture conditions so far applied. The distribution of reducing equivalents to propanediol and hydrogen is also suboptimal. The utilization of the reducing power from pyruvate oxidation for propanediol production is about 60–70% of the theoretical maximum under the present experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01464731
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Growth inhibition by ammonia and use of a pH-controlled feeding strategy for the effective cultivation of Mycobacterium chlorophenolicum (1995)
    Springer
    Applied microbiology and biotechnology 44 (1995), S. 519-525 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The inhibitory effect of ammonia on the growth of the polychlorinated xenobiotic-degrading bacterium Mycobacterium chlorophenolicum was examined. The strain is inhibited by both the ionized and nonionized forms of ammonia. At pH 6.9 50% reduction of the growth rate was observed at 6.8 g l-1 total ammonium. For 23 experiments performed in shake-flask culture at different pH values and ammonium concentrations a growth model based on the extended Monod kinetic fits the data with a deviation of 5.3%. To overcome growth inhibition in bioreactors a pH-controlled feeding strategy was developed for effective cultivation of M. chlorophenolicum at an ammonium level below 0.3 g l-1. The ammonium addition was controlled on-line by the stoichiometric interdependence of ammonium consumption and pH decline. With this on-line control strategy a biomass concentration as high as 26.2 g l-1 can be achieved within less than 1 week of cultivation, compared to a biomass concentration of 15.5 g l-1 in normal batch culture after 2 weeks of cultivation. The yield is also increased from 0.32 g to 0.43 g biomass (g glucose)-1. The strategy developed provides an effective method for the production of biomass of M. chlorophenolicum serving as the inoculum in remediation technologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050592
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Growth inhibition by ammonia and use of a pH-controlled feeding strategy for the effective cultivation of Mycobacterium chlorophenolicum (1995)
    Springer
    Applied microbiology and biotechnology 44 (1995), S. 519-525 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The inhibitory effect of ammonia on the growth of the polychlorinated xenobiotic-degrading bacterium Mycobacterium chlorophenolicum was examined. The strain is inhibited by both the ionized and nonionized forms of ammonia. At pH 6.9 50% reduction of the growth rate was observed at 6.8 g l−1 total ammonium. For 23 experiments performed in shake-flask culture at different pH values and ammonium concentrations a growth model based on the extended Monod kinetic fits the data with a deviation of 5.3%. To overcome growth inhibition in bioreactors a pH-controlled feeding strategy was developed for effective cultivation of M. chlorophenolicum at an ammonium level below 0.3 g l−1. The ammonium addition was controlled on-line by the stoichiometric interdependence of ammonium consumption and pH decline. With this on-line control strategy a biomass concentration as high as 26.2 g l−1 can be achieved within less than 1 week of cultivation, compared to a biomass concentration of 15.5 g l−1 in normal batch culture after 2 weeks of cultivation. The yield is also increased from 0.32 g to 0.43 g biomass (g glucose)−1. The strategy developed provides an effective method for the production of biomass of M. chlorophenolicum serving as the inoculum in remediation technologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169954
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Production of 2,3-butanediol in a membrane bioreactor with cell recycle (1991)
    Springer
    Applied microbiology and biotechnology 34 (1991), S. 463-468 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The production of 2,3-butanediol by Enterobacter aerogenes DSM 30053 was studied in a cell recycle system with a microfiltration module. Emphasis was put on the influence of oxygen supply, cell residence time, dilution rate, and pH. Under optimal conditions a productivity as high as 14.6 g butanediol + acetoin/l per hour was achieved with a product concentration of 54 g/l and a product yield of 88%. This productivity is three times higher than that of an ordinary continuous culture. The achievable final product concentration of a cell recycle system was limited by the accumulation of the inhibiting by-product acetic acid, which increased very rapidly at low dilution rate. To maximize product concentration a fed-batch fermentation was carried out with stepwise pH adaption at high cell density. A final product concentration of 110 g/l was obtained with a productivity of 5.4 g/l per hour and a yield of 97%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180571
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of CO2 absorption on the measurement of CO2 evolution rate in aerobic and anaerobic continuous cultures (1995)
    Springer
    Applied microbiology and biotechnology 42 (1995), S. 688-691 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A general and simple equation is presented to account for the effect of CO2 absorption and the dissociation of carbonic acid in liquid on the measurement of the CO2 evolution rate (QCO2) of both anaerobic and aerobic continuous cultures. For aerobic cultures the same equation applies to the measurement of the respiratory quotient (RQ). The deviation of QCO2 and RQ, calculated from gas-phase measurements, from their true values can be assessed with two parameters: one accounts for the influence of pH, resulting from dissociation of carbonic acid, the other for the influence of operating conditions. Plots are given to show the influences of culture and operating conditions; they may be used as a guideline for choosing proper operating conditions for a reliable measurement of CO2 evolution rate and RQ value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171945
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of substrate limitation on product distribution and H2/CO2 ratio inKlebsiella pneumoniae during anaerobic fermentation of glycerol (1994)
    Springer
    Applied microbiology and biotechnology 42 (1994), S. 222-226 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Product formation during anaerobic degradation of glycerol byKlebsiella pneumoniae DSM 2026, under glycerol limitation and glycerol excess in continugius cultures, has been investigated. Major and minor products and by-products as well as gaseous products were measured. The results indicated a positive correlation between specific glycerol uptake and most product formation rates under glycerol limitation. The production of 1,3-propanediol, lactate, formate, acetate, succinate and the by-products of anaerobic glycerol degradation byK. pneumoniae, acetoin and 2,3-butanediol, was favoured by glycerol excess, while hydrogen generation and ethanol formation were best under glycerol limitation. It was also found that under glycerol limitation the rate of hydrogen evolution was generally higher than the CO2 production rate while under excess glycerol the reverse was true. Hence, on the basis of the ratio of the specific rates of evolution of H2 and CO2 (q H 2/q CO 2), it is possible to infer the existence of glycerol limitation. On the basis of the carbon and available electron balances, which are independent of metabolic pathways, the data are consistent. The NADH2 balance, which took into consideration the pathways of product formation, was also tested to check the validity of the assumed pathways and to check critically the consistency of the data. Good balances were also obtained.[
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00902720
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