[Reuse of recombinant Escherichia coli to produce succinic acid by bioconversion].

The possibility of reusing Escherichia coli cells from the broth for succinic acid production was investigated. Using succinic acid yield and productivity as criterion, we investigated the effects of cell concentration, initial glucose concentration, different neutralizers on the bioconversion. The results revealed that E. coli could convert glucose to succinic acid in a water solution of glucose and a neutralizer. According to the results, the optimal condition was as follows: the cell concentration was 50 (OD600), glucose concentration was 40 g/L and neutralizer was MgCO3. Under the optimum conditions, we carried out the consecutive batch bioconversion in 7 L fermenter. Succinic acid yield reached 91% with the productivity of 3.22 g/(L x h) for the first conversion. For the second conversion, succinic acid yield reached 86% with productivity of 2.04 g/(L x h). Furthermore, we achieved a high mass yield above 83% with the productivity of 1.82 g/(L x h) for the third bioconversion.