Two (carbon)–substrate continuous cultures: Multiple steady states and their stability

Gondo, Shinichiro; Kaushik, Krishna; Venκatasubramanian, Κ.

doi:10.1002/bit.260200914

Cited by 10 publications

(2 citation statements)

References 7 publications

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“…Nevertheless, several proposals-usually derived by combining two or more (modified) Monod terms-were made to describe the utilization of both homologous (21,25,75,132,231,272,274) and heterologous (9,11,12,17,144,156,162) combinations of substrates; for more detail, the reader is referred to the section on kinetics of multiple-nutrient-controlled growth, below). Some of these models were also applied to growth with substrate mixtures in chemostat cultures (75,231,274). Whereas these models could be easily tested for batch-culture growth, the authors were unable to prove their validity for mixed-substrate growth in the chemostat because of the lack of data on steady-state concentrations of growth-controlling substrates.…”

Section: Kinetic Effects During Utilization Of Defined Substratementioning

confidence: 99%

Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

Kovárová-Kovar

Egli

1998

Microbiol Mol Biol Rev

638

260

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SUMMARY Growth kinetics, i.e., the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in microbiology. However, despite more than half a century of research, many fundamental questions about the validity and application of growth kinetics as observed in the laboratory to environmental growth conditions are still unanswered. For pure cultures growing with single substrates, enormous inconsistencies exist in the growth kinetic data reported. The low quality of experimental data has so far hampered the comparison and validation of the different growth models proposed, and only recently have data collected from nutrient-controlled chemostat cultures allowed us to compare different kinetic models on a statistical basis. The problems are mainly due to (i) the analytical difficulty in measuring substrates at growth-controlling concentrations and (ii) the fact that during a kinetic experiment, particularly in batch systems, microorganisms alter their kinetic properties because of adaptation to the changing environment. For example, for Escherichia coli growing with glucose, a physiological long-term adaptation results in a change in KS for glucose from some 5 mg liter−1 to ca. 30 μg liter−1. The data suggest that a dilemma exists, namely, that either “intrinsic” KS (under substrate-controlled conditions in chemostat culture) or μmax (under substrate-excess conditions in batch culture) can be measured but both cannot be determined at the same time. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in ecosystems. However, in nature, microbial cells are exposed to a wide spectrum of potential substrates, many of which they utilize simultaneously (in particular carbon sources). The kinetic data available to date for growth of pure cultures in carbon-controlled continuous culture with defined mixtures of two or more carbon sources (including pollutants) clearly demonstrate that simultaneous utilization results in lowered residual steady-state concentrations of all substrates. This should result in a competitive advantage of a cell capable of mixed-substrate growth because it can grow much faster at low substrate concentrations than one would expect from single-substrate kinetics. Additionally, the relevance of the kinetic principles obtained from defined culture systems with single, mixed, or multicomponent substrates to the kinetics of pollutant degradation as it occurs in the presence of alternative carbon sources in complex environmental systems is discussed. The presented overview indicates that many of the environmentally relevant apects in growth kinetics are still waiting to be discovered, established, and exploited.

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Section: Kinetic Effects During Utilization Of Defined Substratementioning

confidence: 99%

Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

Kovárová-Kovar

Egli

1998

Microbiol Mol Biol Rev

638

260

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“…(5), Table 1). Some of these models were able to predict the dilution rate above which the utilization of secondary substrates ceased (Yoon et al, 1977;Gondo et al, 1978). However, the lack of data made it impossible to evaluate their applicability for growth at lower dilution rates where the substrates were utilized simultaneously.…”

Section: Models Previously Published For Mixed Substrate Growthmentioning

confidence: 99%

Kinetic models for the growth ofEscherichia coli with mixtures of sugars under carbon-limited conditions

Lendenmann

Egli

1998

Biotechnol. Bioeng.

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In natural environments, heterotrophic microorganisms encounter complex mixtures of carbon sources, each of which is present only at very low concentrations. Under such conditions no significant growth could be expected if cells utilized only one of the available carbon compounds as suggested by the principle of diauxic growth. Indeed, there is much evidence that microbial cells utilize many carbon sources simultaneously. In order to predict bacterial growth under such conditions we developed a model describing the specific growth rate as a function of the individual concentrations of several simultaneously utilized carbon substrates. Together with multisubstrate models previously published, this model was evaluated for its ability to describe growth of Escherichia coli during the simultaneous utilization of mixtures of sugars in carbon‐limited continuous culture. Using the μmax and Ks constants determined for single substrate growth with six different sugars, the model was able for most experiments to adequately describe the specific growth rate of the culture, i.e., the experimentally set dilution rate, from the measured concentrations of the individual sugars. The model provides an explanation why bacteria can still grow relatively fast under environmental conditions where the concentrations of carbon substrates are usually extremely low. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:99–107, 1998.

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Dynamics of chemostat in which one microbial population grows on multiple complementary nutrients

Pavlou

1987

Biotech & Bioengineering

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The equations of a chemostat in which one microbial population grows on multiple rate-limiting nutrients are formulated. The dynamics of a chemostat involving growth on complementary nutrients is studied through stability analysis of the system of equations. Some conditions are derived that relate the dynamic behavior of the chemostat to its operating conditions and can be applied to any model for the specific growth rate of the population. It is shown that, if maintenance of the population is neglected, the system exhibits no sustained or damped oscillations. If maintenance of the population is considered, damped oscillations are observed for some operating conditions.

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Two (carbon)–substrate continuous cultures: Multiple steady states and their stability

Cited by 10 publications

References 7 publications

Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

Kinetic models for the growth ofEscherichia coli with mixtures of sugars under carbon-limited conditions

Dynamics of chemostat in which one microbial population grows on multiple complementary nutrients

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