Yeasts as a Glutathione Producer

Introduction. Yeast is a fast-growing single-celled microorganism and an inexpensive source of various biologically active substances, such as antioxidants, e.g. Glutathione (GSH). Antioxidant properties are determined by the presence of sulfhydryl group. The global demand for glutathione is estimated to exceed 9 billion USD at the expense not only of pure crystalized glutathione, but also of glutathione-enriched yeast extracts. In the food industry, glutathione is used to improve the quality of the dough and enhance the taste of various products. The present research featured domestic and foreign studies on the content of glutathione in yeast, methods of biosynthesis, and antioxidant properties. Results and discussion. The content of glutathione ranges from 0.1 to 1% per completely dry biomass (CDB) in wild yeast strains. The fermentative method for the accumulation of glutathione is based on the optimization of the nutrient medium and the use of glutathione precursors, i.e. cysteine, glutamic acid, and glycine. Thus, this method makes it possible to double the content of intracellular glutathione in certain cultivation conditions. The use of non-directed mutagenesis methods can increase glutathione synthesis up to 5% in separate mutant strains, although the mechanism of synthesis is not always clear under such conditions. However, up to 2.27% of glutathione is being formed under directed change of the genome. In addition, the level of glutathione in cells increases under the influence of certain physical factors. For example, glutathione biosynthesis increases by 39% if yeast is exposed to a magnetic field. The enzymatic method requires maintaining the following factors: the presence of precursors (L-glutamic acid, L-cysteine, glycine), ATP, Mg2+ ions to activate GSH1 and GSH2, the pH of the medium, and the introduction of the necessary enzymes into the bioreactor. Hiwever, this method is non-economically profitable in large scale productions due to the needs in use ATP. Conclusion. The survey research demonstrated the effect of technological characteristics of cultivation and biotechnological properties of Saccharomyces cerevisiae on the accumulation of glutathione.