Breeding Of Salt-Tolerant And Ester-Producing Yeast

The breeding of Saccharomyces cerevisiae T-27 (α,tip-, ura-) was focusedin this paper. After UV and Licl treatments, a high salt tolerant mutant—T-27-12(a, trp-, ura-) was obtained. The hereditary characteristics of the salt-tolerantmutant was also analyzed. Then through protoplast fusion to obtain Salt-Tolerantand Ester-Producing Yeast.Saccharomyces cerevisiae T-27 as starting strain, it's cells were mutated with ultraviolet radiation and Licl treatments, a high salt tolerance mutant—T-27-12 (α, trp-, ura-) was obtained. Its salt tolerance increased from 10%to 16%.The hereditary characteristics of the salt-tolerant mutant was also analyzed.The mutant T-27-12 and W-1 were applied as parent strains of protoplast fusion. Protoplast formation conditions of two parent strains were as follow: T-27-12 was treated for 60min with 1.5% Zymolyase at 30℃ to form protoplast, and WS was treated for 90min with 2% Zymolyase at 30℃. The protoplast of T-27-12 and deactivated protoplasts of WS strain fused for 60 min in 35% PEG solution. The fusion rate reached 2.76×10^-6. Comparative studies on cell size, cell volume, DNA content per cell between fusant and its parental strains were made. These data confirm that the fusant is heterozygote of both parental strains.Then, this yeast was added in the later phase of soy sauce fermentation , with short brewing for 20d. Compared with parent strain WS the total ester and the ethyl acetate , 4-EG was changed a little;Compared with Torulopsis, the total ester was increased by 35.29 %. From chromatogram, the ethyl acetate was increased from 20.46mg/L to 28.26mg/L, and 4-EG from 2.30mg/L to 2.86m g/L.