Isolation of glutathione biosynthesis-deficient mutants of Saccharomyces cerevisiae and their use in baker's yeast production

Glutathione biosynthesis-deficient mutants of Saccharomyces cerevisiae 0511 were obtained by mutation under specific conditions. A total of 3388 strains were isolated and among them were found 46 mutants sensitive to methylglyoxal. The intracellular glutathione concentration of mutant strain S. cerevisiae 3033 was 0.0172 g/g dry weight, which was a decrease of >76% compared to that of the parent. The growth of mutant strains S. cerevisiae 3033 and S. cerevisiae 1116 in the medium with glutathione present and absent was compared to that of the parent strain. The sensibility of the baker's yeast strains studied to antifoaming agents, butanol and acetic acid was also investigated. The relationship between glutathione presence in the cell and the sensitivity of strain S. cerevisiae 3033 to antifoaming agents and butanol was ascertained, while such a connection with the presence of acetic acid in the molasses medium used for baker's yeast cultivation was not observed. The higher sensitivity of strain S. cerevisiae 3033 to some chemical compounds in the molasses nutrition medium was shown.