Increasing methionine yield

Abstract

Process for the production of methionine or its derivatives by culturing a microorganism in an appropriate culture medium comprising a source of carbon and a source of sulfur. The microorganism and/or the culture medium are modified in such way that the methionine/carbon source yield is increased. The isolation of methionine or its derivates from the fermentation medium is also described.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a process for the production of methionine or its derivatives by culturing a microorganism in an appropriate culture medium comprising a source of carbon and a source of sulfur. The microorganism and / or the culture medium were modified in a way that the methionine / carbon source yield is increased. The isolation of methionine or its derivates from the fermentation medium is also claimed.PRIOR ART[0002]Sulphur-containing compounds such as cysteine, homocysteine, methionine or S-adenosylmethionine are critical to cellular metabolism and are produced industrially to be used as food or feed additives and pharmaceuticals. In particular methionine, an essential amino acid, which cannot be synthesized by animals, plays an important role in many body functions. Aside from its role in protein biosynthesis, methionine is involved in transmethylation and in the bioavailability of selenium and zinc. Methionine is also directly used as ...

AI Technical Summary

Benefits of technology

[0076]The inventors have shown that the overexpression of at least one of the following genes involved in serine biosynthesis also reduces the production of isoleucine.

[0077]In a more specific embodiment of the invention the inventors have demonstrated that enhanced expression of serA, serB and/or serC reduces the production of the byproduct isoleucine.

[0078]In another specific embodiment of the invention, the production of the byproduct homolanthionine is reduced. Homolanthionine is an amino acid that is produced form activated homoserine and homocysteine (Kromer et al (2006) J Bacteriol 188, 609-18; and patent application WO 2007/051725 by BASF). Homolanthionine is an amino acid that can be separated from methionine only with great difficulty increasing drastically the cost for the production of pure methionine. In addition, homolanthionine comprises two aspartate derived homoserine molecules and a reduced

Problems solved by technology

Nevertheless the racemic mixture does not perform as well as pure L-methionine, as for example in chicken feed additives (Saunderson, C. L. (1985) British Journal of Nutrition 54, 621-633).

Pure L-methionine can be produced from racemic methionine e.g. through the acylase treatment of N-acetyl-D,L-methionine which increases produ

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