Metabolic engineering of Corynebacterium glutamicum strain ATCC13032 to produce l-methionine

l-Methionine-producing strain QW102/pJYW-4-hom(m)-lysC(m)-brnFE was developed from Corynebacterium glutamicum strain ATCC13032, using metabolic engineering strategies. These strategies involved (i) deletion of the gene thrB encoding homoserine kinase to increase the precursor supply, (ii) deletion of the gene mcbR encoding the regulator McbR to release the transcriptional repression to various genes in the l-methionine biosynthetic pathway, (iii) overexpression of the gene lysC(m) encoding feedback-resistant aspartate kinase and the gene hom(m) encoding feedback-resistant homoserine dehydrogenase to further increase the precursor supply, and (iv) overexpression of the gene cluster brnF and brnE encoding the export protein complex BrnFE to increase extracellular l-methionine concentration. QW102/pJYW-4-hom(m)-lysC(m)-brnFE produced 42.2 mM (6.3g/L) l-methionine after 64-H fed-batch fermentation. These results suggest that l-methionine-producing strains can be developed from wild-type C. glutamicum strains by rationally metabolic engineering.