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 technical problem to be solved by the present invention is to provide a method for producing glutathione and a precursor thereof, -glutamylcysteine, at a high yield. As a means for solving the problem, the method for producing glutathione according to the present invention includes step A of reacting L-cysteine and L-glutamic acid under a low-oxygen atmosphere to produce -glutamylcysteine and step B of reacting -glutamylcysteine and glycine under a low-oxygen atmosphere to produce glutathione.

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.

The technical problem to be solved by the present invention is to provide a method for producing oxidized glutathione, GSSG and a precursor thereof, i.e., oxidized -glutamylcysteine, by a simple process. As a means for solving the problem, the method for producing GSSG according to the present invention comprises step A of reacting L-cystine and L-glutamic acid to produce oxidized -glutamylcysteine and step B of reacting oxidized -glutamylcysteine and glycine to produce GSSG.

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

Aggregation is a major cause of the misbehavior of proteins. A system for modifying a protein to create a more stable variant is provided. The method involves identifying non-conserved hydrophobic amino acid residues on the surface of a protein, suitable for mutating to more hydrophilic residues (e.g., charged amino acids). Any number of residues on the surface may be changed to create a variant that is more soluble, resistant to aggregation, has a greater ability to re-fold, and/or is more stable under a variety of conditions. The invention also provides GFP, streptavidin, and GST variants with an increased theoretical net charge created by the inventive technology. Kits are also provided for carrying out such modifications on any protein of interest.

A yeast extract containing 0.2% or more of -Glu-Abu based on dry weight of the yeast extract is produced by culturing a yeast, such as Saccharomyces cervisiae or Candida utilis, in a medium containing a compound selected from Abu (L-2-aminobutyric acid) and -Glu-Abu (L--glutamyl-L-2-aminobutyric acid), and preparing a yeast extract from the obtained cells.

The present invention belongs to the technical field of genetic engineering and fermentation engineering, and in particular relates to a method for preparing S-lactoylglutathione, wherein glutamate, glycine, cysteine and methylglyoxal are used as raw materials, and are converted into S-lactoylglutathione under the catalysis of glutathione synthetase and glyoxalase. According to the present invention, the raw materials with relatively low cost are used for fermentation, the operation is simple, the conversion rate is high, the yield of the prepared S-lactoylglutathione is high, and the method is suitable for batch industrial production.

A micro-organism strain and process for fermentative production of the same. The fermentative production of the substances gamma-glutamyltyrosine and gamma-glutamylphenylalanine by a micro-organism strain which is cultured in a fermentation medium. The fermentation medium is removed from the micro-organisms after the fermentation and gamma-glutamyltyrosine and gamma-glutamylphenylalanine are isolated from the fermentation medium. The microorganism strain contains at least one further gene encoding a glutamate-cysteine ligase and is deficient in glutathione synthetase. For the culture, the fermentation medium is admixed with L-tyrosine and L-phenylalanine.

The present disclosure concerns a method for producing peptides such as glutathione and a microorganism that can be used for such method. One or more embodiments of the first aspect of the present disclosure concern a method for producing peptides such as glutathione comprising culturing a prokaryotic microbial strain in which the expression levels of one or more genes selected from among the gshA gene, the gshB gene, and the gshF gene are enhanced, compared with the expression levels thereof in the wild-type strain thereof in a medium in which the total concentration of cysteine and cystine is 0.5 g/l or lower. The second aspect of the present disclosure concerns a microorganism comprising disruptions of the -glutamyltransferase gene and the glutathione reductase gene and exhibiting the enhanced expression levels of the gshA gene and the gshB or gshF gene.