Methods for producing sulphurous fine chemicals by fermentation using metH-coding cornyeform bacteria

1. A method for the fermentative production of at least one sulfur-containing fine chemical selected from L-methionine and S-adenosylmethionine, which comprises the following steps:

a) fermenting a coryneform bacteria culture thereby producing the desired sulfur-containing fine chemical, wherein the coryneform bacteria expresses at least one heterologous nucleotide sequence which codes for a protein with methionine synthase (metH) activity, wherein the metH-encoding sequence is selected from the group consisting of:

1) a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:1, or a complement thereof; and

2) a nucleic acid molecule comprising a nucleotide sequence encoding a protein comprising an amino acid sequence which is at least 95% identical to the entire amino acid sequence of SEQ ID NO:2, or a complement thereof;

and wherein said sequence is less than 70% identical to the entire metH-encoding sequence from Corynebacterium glutamicum ATCC 13032;

b) concentrating the sulfur-containing fine chemical in the medium or in the bacterial cells, and

c) isolating the sulfur-containing fine chemical.

2. The method of claim 1 wherein the sulfur-containing fine chemical comprises L-methionine.

3. The method of claim 1 , wherein the coding metH sequence is a DNA or RNA which can be replicated in coryneform bacteria or is stably integrated into the chromosome of the coryneform bacteria.

4. The method of claim 3 , wherein the coryneform bacteria is transformed with a plasmid vector comprising at least one copy of the coding metH sequence under the control of a regulatory sequence.

5. The method of claim 1 , wherein the coding metH sequence is overexpressed.

6. The method of claim 1 , wherein the coryneform bacteria further comprises the aspartate kinase-encoding gene lysC that is overexpressed or mutated such that the aspartate kinase-encoding gene lysC encodes a protein having an isoleucine at amino acid residue 311 and the activity of the encoded protein is influenced by metabolic metabolites to a smaller extent.

7. The method of claim 1 , wherein the coryneform bacteria is of the species Corynebacterium glutamicum.

8. The method of claim 1 , wherein the coryneform bacteria is resistant to a methionine biosynthesis inhibitor.

9. A method for producing an L-methionine-containing animal feed additive from fermentation broths, which comprises the following steps:

a) culturing and fermenting of an L-methionine-producing microorganism in a fermentation medium; wherein the microorganism expresses at least one heterologous nucleotide sequence which codes for a protein with methionine synthase (metH) activity, wherein the metH-encoding sequence is selected from the group consisting of (a) a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:1, or a complement thereof, and (b) a nucleic acid molecule comprising a nucleotide sequence encoding a protein comprising an amino acid sequence which is at least 95% identical to the entire amino acid sequence of SEQ ID NO:2, or a complement thereof;

b) removing water from the L-methionine-containing fermentation broth;

c) removing from 0 to 100% by weight of the biomass formed during fermentation; and

d) drying the fermentation broth obtained according to b) and/or c), in order to obtain the animal feed additive in the desired powder or granule form.

10. The method of claim 3 , wherein the coding metH sequence is integrated into the chromosome of the coryneform bacteria.