Fermentation Process Control, Population Dynamics of a Continuous Propagator for Microorganisms

Finn, R. K.; Wilson, Robert E.

doi:10.1021/jf60022a003

Cited by 117 publications

(33 citation statements)

References 4 publications

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“…at which steady-state conditions will be maintained '. Finn & Wilson (1954) also stress this point, and the same idea appears to be implicit in the writings of Adams &Hungate (1950) andNorthrop (1954). If this were so, a continuous culture would be an inherently unstable system and very difficult to operate; moreover, restriction to a single flow-rate would greatly limit its usefulness.…”

Section: Discussionmentioning

confidence: 90%

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The Continuous Culture of Bacteria; a Theoretical and Experimental Study

Herbert¹,

Elsworth²,

Telling³

1956

Journal of General Microbiology

976

416

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SUMMARY: A theoretical treatment of continuous culture is given, which allows quantitative prediction of the steady-state concentrations of bacteria and substrate in the culture, and how these may be expected to vary with change of medium, concentration and flow-rate. The layout and operation of a small pilot plant for the continuous culture of bacteria are described. This plant has been operated continuously for periods of up to 4 months without breakdown or contamination of the culture. No alterations in the properties of the organisms studied have occurred during such periods of continuous culture. Results are given of a series of experiments on the continuous culture of Aerobacter cloacae in a chemically defined medium, designed to allow quantitative comparison with the results predicted by the theory. The relative advantages of batch and continuous culture as production processes are discussed, and it is concluded that continuous culture may usually be expected to show a five to tenfold increase in output as compared with a batch process.The continuous culture of micro-organisms is a technique of increasing importance in microbiology. The essential feature of this technique is that microbial growth in a continuous culture takes place under steady-state conditions; that is, growth occurs a t a constant rate and in a constant environment. Such factors as pH value, concentrations of nutrients, metabolic products and oxygen, which inevitably change during the ' growth cycle ' of a batch culture, are all maintained constant in a continuous culture; moreover, they may be independently controlled by the experimenter. These features of the continuous culture technique make it a valuable research tool, while it offers many advantages, in the form of more economical production techniques, to the industrial microbiologist. Nevertheless, the technique has so far been comparatively little used. (The review of Novick (1955) lists nearly all the work on the subject that has yet appeared.) The reasons for this relative neglect are, we believe, twofold.The first reason is the lack of a generally accepted theoretical background. Continuous culture presents theoretical problems of an essentially kinetic nature which must be solved before the technique can be intelligently applied.

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Section: Discussionmentioning

confidence: 90%

“…This important role of the substrate is not considered in the mathematical papers of Golle (1953), Finn & Wilson (1954) and the other authors mentioned above. This has led to some incorrect conclusions.…”

Section: Discussionmentioning

confidence: 99%

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

Herbert¹,

Elsworth²,

Telling³

1956

Journal of General Microbiology

976

416

View full text Add to dashboard Cite

show abstract

“…It is shown that as time progresses all solution trajectories in the three-dimension solution space approach a plane and thus the three-variable system is equivalent to a model involving only two variables. With this result, we are able to obtain the stability condition for limit cycles bifurcating from a non-washout steady state of the three-variable model, and at the same time rule out the possibility of developing chaotic trajectories through subsequent bifurcations.Oscillatory behavior frequently occurs in both batch and continuous fermentation processes (6,14). In batch cell growth data, we often observe what appears to be random deviations about a smooth exponentially increasing function.…”

mentioning

confidence: 99%

“…Oscillatory behavior frequently occurs in both batch and continuous fermentation processes (6,14). In batch cell growth data, we often observe what appears to be random deviations about a smooth exponentially increasing function.…”

mentioning

confidence: 99%

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On the stability of periodic solutions for a product inhibition model of continuous biological reactors.

Lenbury

Punpocha

1989

J. Gen. Appl. Microbiol.

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A three-variable product-inhibition model of a continuous fermentation process is considered. It is shown that as time progresses all solution trajectories in the three-dimension solution space approach a plane and thus the three-variable system is equivalent to a model involving only two variables. With this result, we are able to obtain the stability condition for limit cycles bifurcating from a non-washout steady state of the three-variable model, and at the same time rule out the possibility of developing chaotic trajectories through subsequent bifurcations.Oscillatory behavior frequently occurs in both batch and continuous fermentation processes (6,14). In batch cell growth data, we often observe what appears to be random deviations about a smooth exponentially increasing function. For most design and control applications such a smoothed function describes the system adequately. However, scaleup from the small batch fermentor to large commercial batch and continuous reactors utilizing microorganisms is still very much an art. As Tanner suggested in his recent work (14), part of the difficulty in scaling up is perhaps directly attributable to the neglect of such small deviations in the process of designing the large vessel. He further stated that if small irregularities in the cell growth were not just random deviation from a smoothed function, then they must be reproducible, lead to recognizable patterns, and ultimately make sense in terms of the underlying biochemical events among the growing microorganisms.Attempts along this line have been made by Lenbury et al. (9,11) who showed that the yield expression must depend on both the cell and substrate levels for oscillations to occur in both the substrate and the cell concentrations.With continuous fermentation, on the other hand, oscillations in the ex-* Address reprint requests to:

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Modelling oscillatory behavior in batch fermentations

Lenbury

Steppan

Park

et al. 1986

Acta Biotechnologica

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A batch fermentation is modelled with constant and variable yield terms. It is shown that the model cannot exhibit oscillations if a constant yield term is used. Oscillations in the cell conccntration, but not in the limiting siibstrate concentration, can be simulated if ii variable yicld function of the limiting substrate is used. Conditions, for which the variable yield needs to satisfy in order to generate oscillations in the cell concentration, are discussed. The primary condition is t h a t the yield must become zero a t the same time that the specific growth rate does. Experimcntnl results exhibiting oscillatory behavior are presented and compared with the proposed model.

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Fermentation Process Control, Population Dynamics of a Continuous Propagator for Microorganisms

Cited by 117 publications

References 4 publications

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

On the stability of periodic solutions for a product inhibition model of continuous biological reactors.

Modelling oscillatory behavior in batch fermentations

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