Preventing mycolic acid reduction in Corynebacterium glutamicum can efficiently increase L-glutamate production

Abstract Corynebacterium glutamicum has been widely utilized for industrial production of various amino acids, especially glutamate, a commonly used food condiment. It has a specific mycolate outer membrane. In this study, the gene cmrA encoding the ketoacyl reductase in the biosynthetic pathway of mycolate was deleted in C. glutamicum ATCC13869, resulting the mutant strain ΔcmrA. As expected, ΔcmrA grown in glucose rich media mainly synthesized keto-glucose monocorynomycolate. Interestingly, L-glutamate production in ΔcmrA increased 10.77-fold, comparing to the control ATCC13869. Based on transcriptomic analysis, the L-glutamate overproduction in C. glutamicum ΔcmrA might be mainly caused by the up-regulation of mscCG expression and the down-regulation of expression of the genes relevant to L-arginine biosynthesis and ODHC. This study provides a novel strategy to improve L-glutamate production in C. glutamicum.