Abstract:To obtain a mutant strain that produces extracellular glutathione （GSH），Saccharmyces Cerevisiae GAQ4 was treated iteratively by UV mutagenesis，and a mutant strain named UV3-10 was finally screened after three times of UV mutagenesis.The extracellular GSH content of UV3-10 was 18.56 mg/L，which was 2.52 times that of original strain GAQ4.To further improve the extracellular GSH content，the fermentation conditions of mutant strain UV3-10 were optimized by single factor experiment.Results showed that the optimal fermentation conditions were 48 h fermentation cycle，fermentation temperature at 34℃，shake flask speed at 140 r/min，shake flask volume of 75 mL/300 mL，and initial pH of 6.5.Under these conditions，the extracellular GSH content reached 52.05 mg/L，which was 2.80 times of that before optimization，achieving the extracellular fermentation production of GSH.