Patent ID: 7745195

Claim:
A method for producing a microorganism wherein said microorganism is obtained by selection of a modified microorganism, having a modified methionine biosynthesis pathway for the biosynthesis of methionine by metabolism of a simple carbon source and methylmercaptan as a source of sulfur, comprising: a) generating a modified microorganism by inactivating, deleting, or inhibiting expression of metE gene in an initial microorganism, wherein ability of said modified microorganism to grow is impaired when grown on a minimal medium containing no methionine, S-adenosylmethionine, homocysteine or cystathionine; b) culturing said modified microorganism obtained in step (a) on said minimal medium, in the presence of methylmercaptan under selection pressure thereby allowing said modified microorganism to proliferate through a methionine biosynthesis pathway to compensate for impaired growth; and c) selecting said microorganism from step (b) able to grow on said minimal medium in presence of methylmercptan, wherein the methionine biosynthesis pathway modifies such that methionine is produced by the metabolism of a simple carbon source and methylmercaptan as a source of sulfur thereby allowing said microorganism to proliferate on said minimal medium containing no methionine, S-adenosylmethionine, homocysteine or cystathionine.