Dynamics of microbial growth and cell composition in batch culture

Wanner, Ursula

doi:10.1016/0378-1097(90)90521-q

Cited by 32 publications

(51 citation statements)

References 63 publications

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“…However, at low starting concentrations (~0.01-0.02 g/l) both substrates are utilized at the same time. Such a transition was observed first by Wanner and Egli [22] and corroborated by Narang [19]. Ramakrishna et al [5] and Venkatesh et al [6] modeled these observations through cybernetic formulations and showed that the order of substrate utilization is so chosen as to maximize the overall specific growth rate.…”

Section: Resultssupporting

confidence: 53%

“…Since E. coli K-12 can shift from sequential utilization to simultaneous utilization when the two substrates are present in small concentrations [5,19,22], this aspect was also investigated for different levels of dispersion. The concentration surfaces (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Fumarate is still utilized faster than glucose at finite Peclet numbers, and the difference in preferences decreases as Pe fi 0. The closeness of preferences when the broth is well-dispersed, leading to simultaneous utilization, is experimentally supported by laboratory fermentations [19,22]. However, now the glucose and fumarate surfaces do not intersect and, unlike the smooth changes during sequential utilization, the approach to nearly equal rates of utilization occurs quite abruptly within a narrow range of 8-10 for Pe.…”

Section: Resultsmentioning

confidence: 99%

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Effect of fluid dispersion on cybernetic control of microbial growth on substitutable substrates

Patnaik

2003

Bioprocess Biosyst Eng

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Many fermentation media contain two or more substrates, which a microorganism utilizes for similar purposes. Depending on the conditions prior to and during a fermentation, the substrates may be utilized in succession or simultaneously. Since it is difficult to portray this behavior through mechanistic models, a cybernetic method was proposed earlier. Here the microorganism chooses the mode of substrate utilization that maximizes its own survival, usually expressed by the growth rate. In a fully dispersed bioreactor, simultaneous utilization generates higher growth rates but leads to low biomass concentrations since this utilization pattern is preferred at low concentrations of the substrates. In this study it has been shown that by allowing less than complete dispersion in the broth it is possible to shift from sequential to simultaneous utilization at high concentrations, thereby enabling both high growth rates and large biomass concentrations. This strategy thus allows the natural incomplete dispersion in large bioreactors to be gainfully exploited.

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Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Effect of fluid dispersion on cybernetic control of microbial growth on substitutable substrates

Patnaik

2003

Bioprocess Biosyst Eng

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“…When E. coli K12 is grown in a mixture of glucose and pyruvate, simultaneous utilisation occurs when the inoculum is precultured on pyruvate alone and sequential utilisation when preculturing is on glucose or the mixture [17]. E. coli ML30 exhibits diauxic growth in a mixture of galactose and glucose when the concentrations are in the 100 mg l A1 range but at low concentrations (about 5 mg l A1 ) there is uptake of both substrates together [18]. For Pseudomonas oxaliticus grown in a medium containing oxalate and formate, simultaneous utilisation occurs when only oxalate is used for preculturing [19].…”

Section: Discussionmentioning

confidence: 99%

Transient sensitivity analysis of a cybernetic model of microbial growth on two substrates

Patnaik

1999

Bioprocess Engineering

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When a microbe has a choice of two substrates for its growth in a fermentation medium, its preference varies with the substrates and with time. This``informed'' choice is conveniently expressed by cybernetic models. For the growth of Klebsiella oxytoca in a medium of glucose and lactose, a one-parameter cybernetic model of growth has been employed in a batch bioreactor to analyse sensitivity of the fermentation to perturbations in the parameter, a (0 £ a £ 1). The sensitivity surfaces in the (a-time) space show interesting variations which are discussed. An important observation is that while growth is best promoted with a 1, i.e. sequential consumption of the substrates [8], low sensitivities require smaller values of a, i.e. simultaneous utilisation. Thus, in a realistic operation it may be necessary to compromise between high growth (with subsequent high productivity) and low sensitivity.

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“…This result is further supported by Varma et al [25] who investigated the relationship between the degree of oxygen limitation and the secretion of acetate, formate, ethanol, lactate and succinate in E. coli fermentations. Wanner and Egli [26] reported that for batch cultures of K. pneumoniae growing on glucose, byproducts in the form of acetate and other unspeci®ed dissolved organic compounds were produced. Therefore, the formation of such byproducts should be of concern for the growth of a wide variety of commonly studied bacterial species.…”

Section: Effect Of Oxygen Concentration In Sparged Gas On Growth Of Ementioning

confidence: 99%

Oxygen availability and the growth of Escherichia coli W3110: A problem exacerbated by scale-up

O’Beirne

Hamer

2000

Bioprocess Engineering

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By examining the effects of oxygen availability on the batch growth of Escherichia coli on glucose the present study seeks to determine the responses of growing cells to varying degrees of oxygen excess, limitation or starvation as might be experienced in an industrial-scale bioreactor. It was found that as the degree of oxygen limitation increases so too does the byproduct acetate production in addition to a concomitant decrease in the substrate based biomass yield coef®cient and maximum speci®c growth rate. Similar, although not as severe, responses to excess oxygen growth conditions were also observed. This result supports the concept of oxygen being potentially toxic to growing organisms, resulting in, at the very least, a degree of inhibition.

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Dynamics of microbial growth and cell composition in batch culture

Cited by 32 publications

References 63 publications

Effect of fluid dispersion on cybernetic control of microbial growth on substitutable substrates

Effect of fluid dispersion on cybernetic control of microbial growth on substitutable substrates

Transient sensitivity analysis of a cybernetic model of microbial growth on two substrates

Oxygen availability and the growth of Escherichia coli W3110: A problem exacerbated by scale-up

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