(582ct) Effect of Coexpression of Cyanobacterial Phosphoenolpyruvate Carboxylase and Carbonic Anhydrase On Succinic Acid Production By Escherichia Coli

In order to study the effect of cyanobacterial phosphoenolpyruvate carboxylase (PEPC) and carbonic anhydrase (CA) coexpression on succinic acid production in Escherichia coli, artificial operon LY204 with ppc and ecaA genes tandem cloned onto the plasmid pTrchisB was constructed and firstly introduced into wild type E. coli strain W1485. The highest level of succinic acid production was obtained in strains with PEPC and CA expression concurrently, when compared with strains individually overexpressing of either PEPC or CA. Secondly this operon was transformed into strains with lactate and formate pathways inactivation to eliminate the competing pathways for succinic acid formation. Thirdly the glucose phosphotransferase system was inactivated to increase the PEP pool, which functioned as the substrate of the PEPC enzyme, besides the HCO₃^-. Results showed that PEPC and CA coexpression was a novel approach to improve the succinic acid production.