Description of the Chemostat

Novick, Aaron; Szilard, Leo

doi:10.1126/science.112.2920.715

Cited by 695 publications

(333 citation statements)

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“…Since its invention in the 1950s, chemostat cultivation of micro-organisms (characterized by growth at a fixed rate in a well-defined and tightly controlled environment) has become a widely used cultivation mode, and has proved to be an excellent tool for quantitative physiological and functional-genomics research (Boer et al, 2003;Novick & Szilard, 1950b;Piper et al, 2002). However, as already noted by Novick (Novick & Szilard, 1950a), one of the inventors of chemostat cultivation, steady-state chemostats exert a strong selective pressure and result, after prolonged cultivation, in the enrichment of evolved genotypes.…”

Section: Introductionmentioning

confidence: 99%

Prolonged selection in aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae causes a partial loss of glycolytic capacity

et al. 2005

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Prolonged cultivation of Saccharomyces cerevisiae in aerobic, glucose-limited chemostat cultures (dilution rate, 0?10 h "1 ) resulted in a progressive decrease of the residual glucose concentration (from 20 to 8 mg l "1 after 200 generations). This increase in the affinity for glucose was accompanied by a fivefold decrease of fermentative capacity, and changes in cellular morphology. These phenotypic changes were retained when single-cell isolates from prolonged cultures were used to inoculate fresh chemostat cultures, indicating that genetic changes were involved. Kinetic analysis of glucose transport in an 'evolved' strain revealed a decreased K m , while V max was slightly increased relative to the parental strain. Apparently, fermentative capacity in the evolved strain was not controlled by glucose uptake. Instead, enzyme assays in cell extracts of the evolved strain revealed strongly decreased capacities of enzymes in the lower part of glycolysis. This decrease was corroborated by genome-wide transcriptome analysis using DNA microarrays. In aerobic batch cultures on 20 g glucose l "1 , the specific growth rate of the evolved strain was lower than that of the parental strain (0?28 and 0?37 h "1 , respectively). Instead of the characteristic instantaneous production of ethanol that is observed when aerobic, glucose-limited cultures of wild-type S. cerevisiae are exposed to excess glucose, the evolved strain exhibited a delay of~90 min before aerobic ethanol formation set in. This study demonstrates that the effects of selection in glucose-limited chemostat cultures extend beyond glucose-transport kinetics. Although extensive physiological analysis offered insight into the underlying cellular processes, the evolutionary 'driving force' for several of the observed changes remains to be elucidated.

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Section: Introductionmentioning

confidence: 99%

Prolonged selection in aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae causes a partial loss of glycolytic capacity

et al. 2005

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“…The chemostat is a biotechnological process of continuous culture developed by Monod (1950) and Novick and Szilard (1950) in which bacteria live in a growth container of constant volume in which liquid is continuously injected.…”

Section: Introductionmentioning

confidence: 99%

Gaussian approximations for chemostat models in finite and infinite dimensions

Cloez¹,

Fritsch

2017

J. Math. Biol.

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Abstract. In a chemostat, bacteria live in a growth container of constant volume in which liquid is injected continuously. Recently, Campillo and Fritsch introduced a massstructured individual-based model to represent this dynamics and proved its convergence to a more classic partial differential equation.In this work, we are interested in the convergence of the fluctuation process. We consider this process in some Sobolev spaces and use central limit theorems on Hilbert space to prove its convergence in law to an infinite-dimensional Gaussian process.As a consequence, we obtain a two-dimensional Gaussian approximation of the CrumpYoung model for which the long time behavior is relatively misunderstood. For this approximation, we derive the invariant distribution and the convergence to it. We also present numerical simulations illustrating our results.

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“…The method of continuous culturing using a chemostat was independently described by Monod 3 and Novick & Szilard 4 in 1950. As originally conceived, cells are grown in a fixed volume of media that is continually diluted by addition of new media and simultaneous removal of old media and cells (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…Indicate the time of inoculation in Iris. 4. Wait approximately 24 hr for cultures to reach early stationary phase.…”

Section: Inoculationmentioning

confidence: 99%

The Use of Chemostats in Microbial Systems Biology

Ziv

Brandt

Gresham

2013

JoVE

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Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated including macromolecular synthesis, metabolism and ultimately, commitment to the cell division cycle. The chemostat, a method of experimentally controlling cell growth rate, provides a powerful means of systematically studying how growth rate impacts cellular processes -including gene expression and metabolism -and the regulatory networks that control the rate of cell growth. When maintained for hundreds of generations chemostats can be used to study adaptive evolution of microbes in environmental conditions that limit cell growth. We describe the principle of chemostat cultures, demonstrate their operation and provide examples of their various applications. Following a period of disuse after their introduction in the middle of the twentieth century, the convergence of genome-scale methodologies with a renewed interest in the regulation of cell growth and the molecular basis of adaptive evolution is stimulating a renaissance in the use of chemostats in biological research. Video LinkThe video component of this article can be found at

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Description of the Chemostat

Cited by 695 publications

References 5 publications

Prolonged selection in aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae causes a partial loss of glycolytic capacity

Prolonged selection in aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae causes a partial loss of glycolytic capacity

Gaussian approximations for chemostat models in finite and infinite dimensions

The Use of Chemostats in Microbial Systems Biology

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