The Breeding Of High Glutathione-Production Strains And Study Of Fermentation Condition

The breeding of high glutathione-producing yeast strain and optimization of cultivation conditions were studied.The different determination methods of glutathione were studied, and DTNB method was modified on the basis of the reserch from the forefathers. The modified DTNB method is simple and rapid with high sensitivity,good accuracy, reproducibility, and could avoid the disturb of cysteine.The biomass and GSH content of 24 yeast strains from different species and genera were tested. Strain (Saccharomyces cerevisiae) SC-20 with high biomass and high GSH content was chosen as original strains. A anti-zinc chloride and anti-mercury chloride mutant DU-20 was obtained and screened from its original strain (Saccharomyces cerevisiae) SC-20 by plasma and UV treatment. The glutathione production of the mutant reached 75.48 mg/L by flask culture, which was 118.40% higher than the original strain, and the glutathione content in the dried cells reached 7.90 mg/g, which was 78.33% higher than the original strain. A desecend of only 5.36% in the glutathione pruduction of the mutant was observed after ten times of subculture. Therefore, the obtained mutant is stable strain that is worthwhile to be studied further.The effect of medium composition and culture condition on the production of glutathione by DU-20 were studied in shaking-flask culture.The effect of factors such as carbon source, nitrogen source, inorganic salt, that affected the GSH production of DU-20 were tested.The optimal fermentation conditions for DU-20 which were determined by direct cross experiment was: 2% glucose, 0.6% yeast extract, 0.3% CH3COONH4, 0.4% Na2HPO4, 0.4% KH2PO4, 0.06% MgS04·7H2O, 0.02% CaC12·2H2O; initial pH nature, amount of medium 30 ml/250 ml flask, inoculation rate 10%, culture time 34 h.