EngineeringCorynebacterium crenatumfor enhancing succinic acid production

Abstract

Succinic acid is valuable due to its historical use in food industry. In this paper, Corynebacterium crenatum was engineered to enhance succinic acid production and the fermentation properties of engineered strains were investigated. The lactate dehydrogenase gene (ldhA) inactivation mutant was first constructed, and then the pyruvate carboxylase gene (pyc) or phosphoenolpyruvate carboxylase gene (ppc) was expressed in the ldhA mutant. The ldhA inactivation resulted in a 52% decrease on glucose consumption, and the succinic acid yield produced by the ldhA mutant was 0.62 g/g, representing a 2-fold increase compared with the yield obtained from the original strain. Overexpression of pyc gene could improve the glucose consumption rate, resulting in a 37% increase compared with the ldhA mutant strain. Meanwhile, the final succinic acid concentration represented a 50% increase than the ldhA mutant strain, and a 106% increase than the original strain. Overexpression of ppc gene had no significant effect. Practical applications The biobased succinic acid and the derivative can be used as food additives. C. crenatum is used for producing amino acid for many years, and it was found that succinic acid and lactic acid are the major products when fermented under anaerobic conditions. This study suggests that C. crenatum can be utilized as a potential cell factory for producing succinic acid after genetic modification. The results obtained in this paper could contribute to the depth development of C. crenatum for producing succinic acid or other products in food industry, not only for amino acid production.