Studies On Production By Fermentation Of Saccharomyces Cerevisiae CNU94

The strain of Saccharomyces cerevisiae B94 was obtained from more than 50 strains of different species and genera of yeasts. It's SOD content is more than 800u/g fresh cell. Based on this strain, a SOD high-producing mutant was obtained through compound mutagenic of UVtreatment to protolast, NTG and ⁶0COγ-rays .The content of the mutant reached 1872u/gfreshcell, which was 134 high than original strains. Genetic stability test showed it was an excellent SOD producer.Based on orthogonal and monofactorial test, the medium and fermentation condition wasstudied.It showed the optimal medium consisted of 2% glucose, 9%(V/V) malt wort, 2%peptone, 1%yeast extract, CuSO₄ 75mmol/ml, ZnSO₄25mmol/ml; the optimal culture condition were as follows: initial pH 5.5,medium cubage was 75ml/500ml, 15% concentration wasinoculated; After 20 hours, H₂O₂ was added to final concentration 1%, then culture to 24 hours. In this condition, the biomass was 5.26g/100ml, SOD activity was 2662u/g fresh cell, SOD production was 1.40×10⁴u/100ml, which was 99% high than original strain.S.cerevisiae CNU94 was purified by procedures consisting of heat, pH regulation,two-steps acetone precipitation and chromatography of DEAE cellulose -32 column. The purified enzymatic specific activity and recovery was 3500u/mg and 58.3%, respectively,the purification multiple was 30.43-fold as much.The activity staining showed Sxervisiace had fourisoenzyme, protein staining showed it reached homogeneous.The types identification showed it was a kind of Cu/Zn SOD.