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  • 1
    Electronic Resource
    Electronic Resource
    A robust fed-batch feeding strategy for optimal parameter estimation for baker's yeast production (1994)
    Springer
    Bioprocess and biosystems engineering 11 (1994), S. 135-144 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Parameter identification of structured models is often a problem in biotechnology, because the poor data situation and the number of unknown parameters only allow for inaccurate estimates. But often only a subset of all kinetic parameters of the model are of interest for production purposes, e.g. for fed-batch cultivation. These parameters should be estimated with a given accuracy. In addition, the experiments for information acquisition with respect to these parameters should be as simple as possible and should consider some practical restrictions. In this contribution a fed-batch feeding strategy is proposed to allow for an accurate estimation of yield and of critical growth rate of baker's yeast. The feeding also allows for economic and stereotyped use of staff and equipment and is therefore suitable for routine use in screening of strains and media. The overall pattern is similar to that one, usually used in production scale to minimize errors by limited model validity. After an initial phase for achieving a reproducible state three different growth rates are adjusted to cover the range of possible critical growth rates. From biomass and ethanol measurements yield and critical growth rate can be estimated with an accuracy of about 2.1%. The fermentation pattern ends up with a constant feeding rate to simulate a limited oxygen transfer rate and to allow for an uptake of residual sugar and ethanol before a dough test can be carried out. Beside experimental results simulations and sensitivity analyses are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00518735
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  • 2
    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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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of substrate limitation on product distribution and H2/CO2 ratio in Klebsiella 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 by Klebsiella pneumoniae DSM 2026, under glycerol limitation and glycerol excess in continuous 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 by K. 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 H2/q CO2), 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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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Data consistency, yield and maintenance coefficient for the growth of Candida lypoytica and Pseudomonas aeruginosa on n-hexadecane (1985)
    Springer
    Applied microbiology and biotechnology 21 (1985), S. 368-373 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary When more than the minimum number of variables are measured, and measurement error is taken into account, the results of parameter estimation depend on which of the measured variables are selected for this purpose. The reparameterization of Pirt's models for growth produces multiresponse models with common parameters. By using the covariate adjustment technique, a unit variate linear model with covariates is obtained. This allows a combined point and interval estimates of biomass energetic yield and maintenance coefficient to be obtained using standard multiple regression programmes. When this method was applied using form I and form II of the Pirt's models, good combined estimates were obtained and compared. Using data from the literature for Candida lipolytica produced reliable results. However, for Pseudomonas aeruginosa, which has been known to produce intermediate products, a modified Pirt's model is required for a good estimate of the biomass energetic yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249982
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  • 5
    Electronic Resource
    Electronic Resource
    Application of material and energy balances in the interpretation of intermediate product build-up in batch growth of Pseudomonas aeruginosa on n-hexadecane (1985)
    Springer
    Applied microbiology and biotechnology 22 (1985), S. 255-258 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary This work is concerned with the application of material and energy balances in an attempt to understand the phenomenon of product build-up when Pseudomonas aeruginosa is grown on n-hexadecane in a batch fermentor. It is shown that the organism accumulates a polyactide, called poly-B-hydroxybutyrate (PHB) during early stages of growth and metabolizes it at later stages of growth. This explains the low carbon and available electron balances which have been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00252026
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of the respiro-fermentative growth of Saccharomyces cerevisiae on glucose in a fed-batch fermentation strategy for accurate parameter estimation (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 664-669 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Analysis of the respiro-fermentative growth of a strain of Saccharomyces cerevisiae, DSM 2155 on glucose, in a simulated 5-phase feeding strategy of fed-batch cultures executed on the Universal BIoprocess CONtrol (UBICON) system, was carried out. There was a good agreement between the estimated and the simulated values of specific growth rates. In this study, which was designed to span 0.20–0.23 h–1 growth rates before returning to lower growth rates, the critical dilution rate at which the switch between purely oxidative and respiro-fermentative growth takes place was not observed. The biomass yield, specific substrate uptake and O2 consumption rates as well as the consistency of the data using both carbon and available electron balances were examined. A high average value of true biomass energetic yield, ηmax=0.707, and a low value of maintenance coefficient, me=0.0114 h–1, were obtained indicating that the organism was in no danger from the ethanol produced as a high-density fermentation with a yeast concentration above 54 g l–1 was possible within a period of 24 h. The yeast produced also had good dough-leavening characteristics. Thus it is possible to operate a yeast plant without resorting to using respiratory quotient, which may be problematic, as the controlling parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167282
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of the respiro-fermentative growth of Saccharomyces cerevisiae on glucose in a fed-batch fermentation strategy for accurate parameter estimation (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 664-669 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Analysis of the respiro-fermentive growth of a strain of Saccharomyces cerevisiae, DSM 2155 on glucose, in a simulated 5-phase feeding strategy of fedbatch cultures executed on the Universal BIoprocess CONtrol (UBICON) system, was carried out. There was a good agreement between the estimated and the simulated values of specific growth rates. In this study, which was designed to span 0.20–0.23 h−1 growth rates before returning to lower growth rates, the critical dilution rate at which the switch between purely oxidative and respiro-fermentative growth takes was not observed. The biomass yield, specific substrate uptake and O2 consumption rates as well as the consistency of the data using both carbon and available electron balances were examined. A high average value of true biomass energetic yield, ηmax = 0.707, and a low value of maintenance coefficient, me = 0.0114 h−1, were obtained indicating that the organism was in no danger from the ethanol produced as a high-density fermentation with a yeast concentration above 54 g 1−1 was possible within a period of 24 h. The yeast produced also had good dough-leavening characteristics. Thus it is possible to operate a yeast plant without resorting to using respiratory quotient, which may be problematic, as the controlling parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167282
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Estimation of parameters where dependent observations are related by equality constraints (1984)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 30 (1984), S. 747-757 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pirt's model for microbial growth and product formation are reparameterized to obtain multiresponse models with common parameters. The dependent variables in the models are related through the available electron and carbon balance constraints. Covariance adjustment is used to reduce the growth model to a unit variate linear model with covariates. Therefore, standard multiple regression programs can be used to obtain combined point and interval estimates of true biomass energetic yield, true product yield and maintenance coefficient. This approach may yield “better” estimates than the maximum likelihood approach when an appropriately selected subset of covariates is used. Nonlinear estimation procedures are also considered; these procedures are efficient with few responses; however, as the number of responses per observation increase, they may require a lot of computing time. For illustration several data from the biochemical engineering literature are analyzed by the proposed methods.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690300508
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Application of data consistency tests and new parameter estimation methods to microbial growth on corn dust in batch culture (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 2333-2360 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The microorganism Candida utilis was grown on both filtered and unfiltered substrate obtained from enzymatic hydrolysis of starch in corn dust. For growth on filtered substrate, the average integrated biomass energetic yield value based on biomass-substrate data was η = 0.55 and for growth on unfiltered substrate an average yield value of η = 0.59 was obtained. Material and energy balances showed that the presence of unfiltered corn residue in the media had no significant effect on the yields. Statistical methods were developed and used to obtain best estimates of the growth parameters. Values of the biomass energetic yield corrected for maintenance (ηmax = 0.619) and the maintenance coefficient (me = 0.043) were obtained for growth on filtered substrate. Values of ηmax = 0.741 and me = 0.142 were obtained for the growth on unfiltered substrate. The consistency of data and parameter estimates was relatively good for filtered substrate; however, parameter estimates for unfiltered substrate were not consistent. Growth experiments without filtration of the products of starch hydrolysis resulted in protein-enriched products with about 39.73% protein.
    Additional Material: 14 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260231015
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Maximum likelihood estimation of growth yields (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 633-649 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work is concerned with statistical methods to estimate yield and maintenance parameters associated with microbial growth. For a given dilution rate, an experimenter typically measures substrate concentration, oxygen utilization rate, the rate of carbon dioxide evolution, and biomass concentration. These correlated response variables each contain information about the maintenance and yield parameters of interest. A maximum likelihood estimator which combines this correlated information for the yield and maintenance parameters is proposed, evaluated, and tested on literature data. Both point and interval estimators are considered.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260240309
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