After deleting the gene encoding succinate dehydrogenase, Corynebacterium glutamicum can produce succinate and a considerable amount of acetate and pyruvate as by-products from glucose metabolism, under aerobic conditions. Recently, we identified ynfM in Pantoea ananatis (PaynfM) as a gene encoding a dicarboxylate transporter and found a homologous gene (CgynfM) in C. glutamicum. In this study, we examined dicarboxylate production using C. glutamicum strains expressing CgynfM. When C. glutamicum expressing the CgynfM gene was cultured under aerobic conditions, the sugar-consumption rate increased significantly, succinate accumulation increased from 66 mM to 110 mM, and pyruvate and acetate co-production decreased significantly. Pyruvate decreased from 120 mM to 6.2 mM, and acetate decreased to undetectable level. CgYnfM restored succinate production under anaerobic conditions in C. glutamicum strain AJ110655ΔsucE1, in which the gene encoding the major succinate exporter (sucE1) was deleted. CgynfM expression also increased α-ketoglutarate production from 5.1 mM to 24 mM under anaerobic conditions. Collectively, these results suggest that YnfM from C. glutamicum functions as a dicarboxylate transporter that is applicable to the succinate production.
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