Provided is a process for the preparation of L-methionine in an enzymatic reaction utilizing dimethyl disulfide (DMDS) a precursor of L-methionine, and an organic reducing compound. In the process, methyl mercaptan can be formed by the enzymatic hydrogenolysis of the DMDS.

Provided is an enzymatic process for preparing L-methionine from diethyl disulfide.

The present invention is an inducible coexpression system, capable of controlled induction of expression of each gene product.

One or more embodiments of the present invention provide a microbial strain with improved productivity of ?-glutamylcysteine, bis-?-glutamylcystine, ?-glutamylcystine, reduced glutathione, and/or oxidized glutathione. Such microbial strain has disruption of [1] a gene encoding ?-glutamyltransferase and [2] a gene encoding phosphoglycerate mutase and enhanced expression of [3] a gene encoding glutamate-cysteine ligase and/or a gene encoding glutathione synthetase or [4] a gene encoding bifunctional glutathione synthetase. This invention also discloses a method for producing the substances mentioned above via culture of the microbial strain.

The present invention is an inducible coexpression system, capable of controlled induction of expression of each gene product.

Provided is a process for the preparation of L-methionine in an enzymatic reaction utilizing dimethyl disulfide (DMDS) a precursor of L-methionine, and an organic reducing compound. In the process, methyl mercaptan can be formed by the enzymatic hydrogenolysis of the DMDS.

Provided is an enzymatic process for preparing L-methionine from diethyl disulfide.

Provided is an enzymatic process for the preparation of a mercaptan of formula RSH from disulfides utilizing hydrogen.

The present invention aims to provide a yeast that is genetically modified so as to more highly produce glutathione, and a method of producing glutathione utilizing the yeast. The present invention provides a method of producing glutathione, including culturing a yeast whose thiol oxidase activity is increased as compared to the parent strain in a culture medium to produce glutathione, and recovering glutathione from the cultured broth obtained.

The present invention provides host cells for use in an inducible coexpression system that is capable of controlled induction of expression of each gene product.