ISSN:
0006-3592
Keywords:
2,3-butanediol
;
microaerobic culture
;
TCA cycle
;
oxygen utilization
;
reactor design
;
mixing
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
A new parameter, the relative utilization of tricarboxylic acid (TCA) cycle β, is introduced to quantitatively account for the involvement of fermentation pathways and TCA cycle in the utilization of oxygen under oxygen-limiting (microaerobic) conditions. With the facultative anaerobe Enterobacter aerogenes, which produces 2,3-butanediol, a method is proposed to calculate β from measurement of metabolites and exhaust gas. In continuous culture β was found to be small under oxygen limitation, indicating that the fermentation pathways were preferred over the TCA cycle and oxygen was almost entirely consumed through oxidation of reduced nicotinamide adenine dinucleotide (NADH2) released by fermentation under these conditions. The increase of β at high oxygen supply revealed a saturation of oxygen utilization through fermentation pathways. It could be concluded that, for the optimal performance of a microaerobic culture, oxygen uptake rate must be kept at such a level that as much NADH2 as possible from fermentation pathways is oxidized by oxygen, and at the same time the utilization of TCA cycle is kept at a minimum. As the dynamics of the microaerobic culture can be fast, a significant effect of reactor hydrodynamics, i.e., mixing, on the overall performance can be expected. This was confirmed experimentally, and the parameter β proved to be a useful reactor design criterium for the microaerobic cultivation. © 1992 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260400911
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