Abstract:Both of the phosphoenolpyruvate carboxylase (PPC) and phosphoenolpyruvate carboxykinase (PCK) could catalyze the reaction from phosphoenolpyruvate (PEP) to oxaloacetic acid (OAA) in the pathways of anaerobic mixed acid fermentation for E. coli. In addition, the reaction catalyzed by PCK generates ATP, which is more beneficial to the growth of the strain and the succinic acid production theoretically. In this study, we constructed a ppc defective strain using λ-Red homologous recombination system with the E. coli W3110 (△pfl, △ldh) as the parent strain. Based on that, Bacillus subtilis pck was overexpressed. The preliminary anaerobic fermentation experiments showed that both strains partially recovered the ability to consume glucose through the overexpression of pck. Besides, the ppc defective strain showed the most excellent performance, the rate of glucose consumption and succinate production were 4.2 and 15.3 folds as much as those of the parent strain, respectively.
