Method for producing L-methionine by fermentation

A method for producing L-methionine which comprises culturing a recombinant Escherichia bacterium in a medium to produce and accumulate L-methionine in the medium in an amount in excess of the corresponding unmodified Escherichia bacterium, and collecting the L-methionine from the medium, wherein

• the bacterium is deficient in repressor of L-methionine biosynthesis system encoded by the endogenous metJ gene and has L-methionine productivity,
• activity of intracellular homoserine transsuccinylase encoded by the metA gene of a Escherichia bacterium is increased compared to an unmodified Escherichia bacterium by increasing copy number of the metA gene including its own promoter, or replacing the native promoter with a stronger promoter, and
• the bacterium comprises at least one characteristic selected from the group consisting of:
• (a) exhibits reduced activity of intracellular S-adenosylmethionine synthetase encoded by the endogenous metK gene as compared to an unmodified Escherichia bacterium;
• (b) exhibits L-threonine auxotrophy;
• (c) exhibits enhanced activity of intracellular cystathionine γ-synthase encoded by the metB gene of a Escherichia bacterium and enhanced activity of intracellular aspartokinase-homoserine dehydrogenase II encoded by the metL gene of a Escherichia bacterium as compared to an unmodified Escherichia bacterium by increasing copy number of each of the genes including their own promoters, or replacing the native promoter with a stronger promoter;
• and
• (d) has a homoserine transsucinylase for which concerted inhibition by L-methionine and S-adenosylmethionine is desensitized, wherein the homoserine transsuccinylase comprising the amino acid sequence of SEQ ID NO:
• 26 contains at least one amino acid replacement wherein said at least one amino acid replacement is independently selected from the group consisting of replacement of the amino acid residue Arg-27 with cysteine, replacement of the amino acid residue Ile-296 with serine, and replacement of the amino acid residue Pro-298 with leucine.