Restricted oxygen supply and excretion of metabolites

Vollbrecht, D.; Nawawy, M. A. El

doi:10.1007/bf00499994

Cited by 19 publications

(3 citation statements)

References 8 publications

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“…When E. coli cultures are exposed to a gradually increasing degree of oxygen limitation, mixed acid fermentation products (acetate, ethanol, formate, hydrogen gas, lactate, succinate) appear (Varma et al, 1993;Vollbrecht, 1982). Of these products only acetate is also produced when E. coli is grown aerobically in the presence of excess glucose (over¯ow metabolism) (Holms, 1996;Lee, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, it has been shown that formate, produced in an oxygen-limited compartment of the reactor, is not consumed as fast as acetate when returning to a region with a high oxygen level (Xu et al, 1999). Of these metabolites, acetate was detected before formate in a batch phase when E. coli was exposed to increasing oxygen limiting conditions (Vollbrecht, 1982). However, the concentration of the latter increased ®rst after the dissolved oxygen tension (DOT) approached zero, while the DOT in the present investigation was maintained above 30% saturation.…”

Section: Introductionmentioning

confidence: 99%

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Formate accumulation due to DNA release in aerobic cultivations of Escherichia coli

Castan¹,

Enfors

2001

Biotech & Bioengineering

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Three different aerobic fed-batch processes of Escherichia coli were studied, two for the production of a recombinant protein and one process with a wild-type E. coli strain. In all three processes, an accumulation of formate could be observed in the latter part of the process. Analysis of the concentration of DNA in the medium revealed that the release of DNA coincided with the accumulation of formate. It was found that increasing concentrations of DNA correlated in almost linearly increasing concentrations of formate. Formate accumulation is caused by mixed acid fermentation, although no oxygen limitation was measured with the DO electrode. It is proposed that extracellular DNA restrained mass transfer between the bulk medium and the cell. To investigate if the DNA accumulation caused formate production, DNA was removed by continuous feeding of a DNA binding polymer to the medium. The addition of the polymer decreased the content of free DNA in the broth and the formate was reassimilated. Furthermore, additional DNA early in the process resulted in early formate accumulation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Formate accumulation due to DNA release in aerobic cultivations of Escherichia coli

Castan¹,

Enfors

2001

Biotech & Bioengineering

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“…&CA was estimated according to Eq. (20), and is shown in Figure 10 to decrease significantly as D decreases, approaching zero activity at D = 0.15 h-l.…”

Section: Oxygen-limited Continuous Culturementioning

confidence: 88%

An energetic model for oxygen‐limited metabolism

Beronio¹,

Tsao

1993

Biotech & Bioengineering

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Microbial production of 2,3-butanediol by Klebsiella oxytoca occurs under conditions of an oxygen limitation. The extent to which substrate is oxidized to 2,3-butanediol and its coproducts, (acetic acid, acetoin, and ethanol) and the relative flow rates of substrate to energetic and biosynthetic pathways are controlled by the degree of oxygen limitation. Two energetic relationships which describe the response to an oxygen limitation have been derived. The first relationship describes the coupling between growth and energy production observed under oxygen-limited conditions. This allows calculation of energetic parameters and modeling of the cell mass and substrate profiles in terms of the degree of oxygen limitation only. The second relationship describes the average degree of oxidation and the rate of the end-product flow. The model has been tested with both batch and continuous culture. During these kinetic studies, two phases of growth have been observed: energy-coupled growth, which was described above; and, energy-uncoupled growth, which arises when the degree of oxygen limitation reaches a critical value. Optimal culture performance with respect to 2,3-butanediol productivity occurs during energy-coupled growth.

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PHB and Other Polhydroxyalkanoic Acids

Steinbüchel¹

1996

Biotechnology

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Restricted oxygen supply and excretion of metabolites

Cited by 19 publications

References 8 publications

Formate accumulation due to DNA release in aerobic cultivations of Escherichia coli

Formate accumulation due to DNA release in aerobic cultivations of Escherichia coli

An energetic model for oxygen‐limited metabolism

PHB and Other Polhydroxyalkanoic Acids

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