通过抑制酿酒酵母乙醇发酵中的甘油产率提高乙醇产率

In ethanol fermentation of Saccharomyces cerevisiae (S.cerevisiae),glycerol is one of t11e main by-products.The purpose of this investigation was to increase ethanol yield through minimizing glycerol yield by using mutants in which FPSl encoding a channel protein that mediates glycerol export and GPD2 encoding one of glycerol-3-phosphate dehydrogenase were knocked-out using one-step gene replacement.GLTl and GLNl that encode glutamate synthase and glutamine synthetase,respectively,were overexpressed using two-step gene replacement in fps1△Agpd2△ mutant.The fermentation properties of ZAL69(fps1△::JLEU2 gpd2△::URA3)and ZAL808(fps1△::LEU2 gpd2△::URA3 PPGKI-GL71 PPGKI-GLNI)under microaerobic conditions were investigated and compared with those of wild type(DC124).Consumption of glucose,yield of ethanol,yield of glycerol,acetic acid,and pyruvic acid were monitored.Compared with wild type.the ethanol yield of ZAL69 and ZAL808 were improved by 13.17%and 6.66%,respectively,whereas glycerol yield decreased by 37.4%and 41.7%.Meanwhile,acetic acid yield and pyruvic acid yield decreased dramatically compared to wild type.Our results indicate that FPS1 and GPD2 deletion of S.cerevisiae resulted in reduced glycerol yield and increased ethanol yield.but simultaneous overexpression of GLTl and GLN1-in fps1△gpd2△ mutant did not have a higher ethanol yield thall fps1△gpd2△ mutant.