摘要
In ethanol fermentation of Saccharomyces cerevisiae （S. cerevisiae）, glycerol is one of the main by-products. The purpose of this investigation was to increase ethanol yield through minimizing glycerol yield by using mutants in which FPS1 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. GLT1 and GLN1 that encode glutamate synthase and glutamine synth.etase, respectively,were overexpressed using two-step gene replacment in fpsl△gpd2△ mutant.The fermentation properties of ZAL69（fpsl△：：LEU2 gpd2△：：URA3） and ZAL808 （fps1△：：LEU2 gpd2△：：URA3 PPGK1-GLT1 PPGK1-GLN1） 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 acia yield and pyruvic acid yield aecreasea aramatlcally comparea 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 GLT1 and GLN1 infps1△gpd2△ mutant did not have a higher ethanol yield thanfps1△gpd2△ mutant.
在 Saccharomyces cerevisiae 的乙醇发酵(S。cerevisiae ) ，甘油是主要副产品之一。这调查的目的是通过由使用在编码调停的隧道蛋白质的 FPS1，编码 glycerol-3-phosphate 脱氢酶之一的甘油出口和 GPD2 用一步舞基因代替是敲门外面的异种最小化甘油产量增加乙醇产量。分别地，编码 glutamate synthase 和夫酸安合成酶的 GLT1 和 GLN1 是用在 fps1 螖 gpd2 螖异种的二拍子的圆舞基因代替的 overexpressed。ZAL69 的发酵性质(fps1 螖:: LEU2 gpd2 螖:: URA3 ) 并且 ZAL808 (fps1 螖:: LEU2 gpd2 螖:: URA3 PPGK1-GLT1 PPGK1-GLN1 ) 在 microaerobic 下面，条件被调查并且与那些相比野类型(DC124 ) 。葡萄糖，乙醇的收益，甘油的收益，醋酸，和焦葡萄酸酸的消费被监视。与野类型相比，分别地，而甘油产量由 37.4 % 和 41.7 % 减少了， ZAL69 和 ZAL808 的乙醇收益被 13.17% 和 6.66 % 改进。同时，醋酸收益和焦葡萄酸酸产量与野类型相比戏剧性地减少了。我们的结果显示 S 的那 FPS1 和 GPD2 删除。cerevisiae 导致了减少的甘油产量并且在 fps1 螖 gpd2 螖增加了 GLT1 和 GLN1 的乙醇产量，而是同时的 overexpression 异种没比 fps1 螖 gpd2 螖有更高的乙醇收益变异。
基金
the National High Technology Research and Development Program of China(2002AA647040)
