The purpose of the present invention is to provide a method for producing selenoneine that allows production of selenoneine at higher yields, even if an inorganic selenium compound is used as a selenium compound. This purpose can be achieved by a method for producing selenoneine, comprising the step of applying histidine and a selenium compound to a transformant to obtain selenoneine, wherein the transformant has at least one gene selected from the group consisting of a SatA gene, a CysB gene and a MetR gene, and an EgtA gene inserted therein and can overexpress the inserted genes.

Genetically modified microorganism strains for the fermentative production of cysteine provide higher yields of L-cysteine or L-cystine during fermentation. Cysteine production is improved in the genetically modified microorganism strains by attenuating or inactivating phosphoenolpyruvate synthase enzyme activity, alone or in combination with the overexpression of efflux proteins and proteins that reduce feedback inhibition by cysteine and by serine.

This invention is intended to improve glutathione productivity by fermentation using microorganisms. This invention relates to a microbial strain capable of overexpression of γ-glutamylcysteine, bis-γ-glutamylcystine, γ-glutamylcystine, reduced glutathione, and/or oxidized glutathione in which the expression level of a gene encoding serine-O-acetyltransferase (EC:2.3.1.30) is enhanced and a method involving the use of such microbial strain.

The present invention relates to an L-cysteine-producing mutant microorganism having introduced therein genes encoding enzymes which are involved in the L-cysteine metabolic pathway, and more particularly to an L-cysteine-producing mutant microorganism having introduced therein cysE, cysK and cysR, which are genes encoding enzymes which are involved in the L-cysteine metabolic pathway, and to a method of producing L-cysteine using the mutant microorganism. According to the present invention, L-cysteine can be produced with high efficiency as a result of regulating metabolic fluxes associated with the L-cysteine metabolic pathway of the mutant microorganism and regulating a system for supplying a sulfur source essential for synthesis of L-cysteine.

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 relates to an L-cysteine-producing mutant microorganism having introduced therein genes encoding enzymes which are involved in the L-cysteine metabolic pathway, and more particularly to an L-cysteine-producing mutant microorganism having introduced therein cysE, cysK and cysR, which are genes encoding enzymes which are involved in the L-cysteine metabolic pathway, and to a method of producing L-cysteine using the mutant microorganism. According to the present invention, L-cysteine can be produced with high efficiency as a result of regulating metabolic fluxes associated with the L-cysteine metabolic pathway of the mutant microorganism and regulating a system for supplying a sulfur source essential for synthesis of L-cysteine.

The purpose of the present invention is to provide a method for producing selenoneine that allows production of selenoneine at higher yields, even if an inorganic selenium compound is used as a selenium compound. This purpose can be achieved by a method for producing selenoneine, comprising the step of applying histidine and a selenium compound to a transformant to obtain selenoneine, wherein the transformant has at least one gene selected from the group consisting of a SatA gene, a CysB gene and a MetR gene, and an EgtA gene inserted therein and can overexpress the inserted genes.