| 초록 |
A pfl ldhA double mutant Escherichia coli strain NZN111 was used to produce succinic acid by overexpressing the E. coli malic enzyme. E. coli strain NZN111 harboring pTrcML produced 6 and 8 g/L of succinic acid from 20 g/L of glucose in flask culture at 37oC and 30oC, respectively. When NZN111(pTrcML) was cultured at 30oC with intermittent glucose feeding, the final succinic acid concentration obtained was 9.5 g/L, and the ratio of succinic acid to acetic acid was 13:1. This system could not be analyzed by conventional metabolic flux analysis techniques, since some pyruvate and succinic acid were intracellularly accumulated. Therefore, a new flux analysis method was proposed by introducing intracellular pyruvate and succinic acid pools. By this new method, the concentrations of intracellular metabolites were successfully predicted, and the differences between the measured and calculated reaction rates could be considerably reduced. |
