提高木糖代谢能力的酿酒酵母Y5-X3的初步构建

Construction of Saccharomyces cerevisiae Y5-X3 with enhanced ability of xylose metabolism

为获得能够发酵木糖和葡萄糖的新菌种,文中采用实验室专利菌株Saccharomyces cerevisiae Y5为宿主菌,分别采用热带假丝酵母(Candida tropicalis)和休哈塔假丝酵母(Candida shehatae)作为木糖代谢关键酶XYL1,XYL2的来源,利用酵母整合载体将XYL1,XYL2基因导入S.cerevisiae Y5基因组,同时超表达S.cerevisiae Y5内源木酮糖激酶基因XKS1,获得了酿酒酵母新菌种S.cerevisiae Y5-X3。结果表明,S.cere-visiae Y5-X3在摇瓶共发酵3%葡萄糖和2%木糖时能够利用木糖产乙醇,木糖消耗量和乙醇产量分别比宿主菌提高102.93%和12.54%,发酵2%木糖时木糖的消耗量是宿主菌的2.7倍。XKS1基因的超表达促进了木糖代谢,大大减少了木糖醇积累,提高了乙醇产量。

In order to get a new strain which can ferment both xylose and glucose,the article chose the patent strain Saccharomyces cerevisiae Y5 as the host strain,Candida shehatae and Candida tropicalis as the source of key xylose metablism genes XYL1,XYL2 respectively,transformed them into the genome of S.cerevisiae Y5 and over-expressing endogenesis XKS1（xylulose kinase）,the new Saccharomyces cerevisiae were obtained.The result indicated that the recombinant strain S.cerevisiae Y5-X3 could ferment xylose to ethanol during the fermentation in the medium containing 3% glucose and 2% xylose,with the consumption of xylose and ethanol yield was enhanced by 102.93% and 12.54% compared to the host strain respectively.The xylose consumption of S.cerevisiae Y5-X3 was 2.7 times than that from the host strain during the fermentation of 2% xylose.Over-expression of XKS1 enhanced xylose metabolism,reduced the xylitol accumulation and increased the ethanol production.