Efficient screening a high glutathione-content mutant of Saccharomyces cerevisiae by flow cytometry

Screening for the high glutathione-content microorganisms is an important technique for industrial production of glutathione. In this study, the intracellular glutathione-content was investigated to correlate better with the fluorescence emission at around 490 nm in the yeast. Therefore, we developed an efficient flow cytometry method to screen for the higher glutathione-content mutant of Saccharomyces cerevisiae by measuring the intensity of fluorescence emitted from the cell. The library of mutants was generated by ethyl methanesulfonate mutagenesis and mutant G-143 was isolated which produced 35% higher glutathione than the parent strain in the flask culture, and the glutathione yield was 37% increased when G-143 was scaled up to a 5 L fermentor for glutathione was the intracellular product.