| Autor: |
Jiang-feng Ma, Min Jiang, Ke-quan Chen, Bing Xu, Shu-wen Liu, Ping Wei, Han-jie Ying, Ho-Nam Chang, Ping-kai Ouyang |
| Zdroj: |
Bioprocess & Biosystems Engineering; May2011, Vol. 34 Issue 4, p411-418, 8p, 1 Diagram, 3 Charts, 5 Graphs |
| Abstrakt: |
Escherichia coli AFP111, a pflB, ldhA, ptsG triple mutant of E. coli W1485, can be recovered for additional succinate production in fresh medium after two-stage fermentation (an aerobic growth stage followed by an anaerobic production stage). However, the specific productivity is lower than that of two-stage fermentation. In this study, three strategies were compared for reusing the cells. It was found when cells were aerobically cultivated at the end of two-stage fermentation without supplementing any carbon source, metabolites (mainly succinate and acetate) could be consumed. As a result, enzyme activities involved in the reductive arm of tricarboxylic acid cycle and the glyoxylate shunt were enhanced, yielding a succinate specific productivity above $$ 1 2 5\;{\text{mg}}\;{\text{g}}_{\rm DCW}^{ - 1} \,{\text{h}}^{ - 1} $$ and a mass yield above 0.90 g g in the subsequent anaerobic fermentation. In addition, the intracellular NADH of cells subjected to aerobic cultivation with metabolites increased by more than 3.6 times and the ratio of NADH to NAD increased from 0.4 to 1.3, which were both favorable for driving the TCA branch to succinate. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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