Patent ID: 8148117

Claim:
A process for the preparation of L-methionine, which comprises the following steps: cultivating and/or fermenting a microorganism, wherein said microorganism is a Corynebacterium glutamicum cell that has its endogenous mcrB and metB genes disrupted by a deletion or an insertion, wherein said microorganism produces or overproduces L-methionine and in which the formation and/or accumulation of homolanthionine in the methionine pathway is reduced and/or prevented, wherein the production of an endogenous transcriptional regulator protein (McbR) is reduced compared to that of the corresponding wild-type microorganism, and the microorganism (a) has introduced therein a heterologous gene coding for a cystathionine-β-lyase (MetC) mutant which is capable of efficiently converting homolanthionine into homocysteine, (b) has introduced therein a heterologous gene coding for a cystathionine-γ-synthase (MetB) mutant which is capable of efficiently converting O-acetyl-homoserine and cysteine into cystathione and which is not capable of converting O-acetyl-homoserine and homocysteine into homolanthionine, or (c) produces more of a protein selected from the group consisting of a protein having the activity of cob(I)alamin dependent methionine synthase I (MetH), and cob(I)alamin independent methionine synthase II (MetE) than the corresponding wild-type microorganism; and isolating L-methionine.