高效发酵木糖生产乙醇酵母菌株的构建

获得高效发酵木糖生产乙醇的酵母菌株是木质纤维素生物转化生产燃料乙醇的重要前提。在4%乙醇驯化的基础上，选择了乙醇耐性提高的休哈塔假丝酵母（Candida shehatae）CICC1766菌株进一步进行紫外诱变，得到了木糖发酵性能较强的呼吸缺陷型突变体，并与乙醇发酵性能良好的酿酒酵母（Saccharomyces cerevisiae）ATCC4126进行原生质体融合。采用单亲灭活法对休哈塔假丝酵母原生质体进行紫外灭活，在聚乙二醇（PEG）诱导下融合，对得到的融合子进行木糖发酵能力测定，选择到了一株能够更好地利用木糖产乙醇，并且木糖发酵性能比亲本得到明显提高的融合子F6，此融合子发酵50 g/L木糖，最高乙醇浓度达到18.75g/L，乙醇得率为0.375，达到理论转化值0.511的73.4%。与原始出发菌株CICC1766相比，乙醇产量提高了28%。

Breeding of Yeast Fusant for Efficient Ethanol Fermentation from Xylose

Yeast strains with improved ethanol yield are important for efficient bioconversion of lignocellulosic biomass for fuel ethanol. In this study, Candida shehatae CICC1766 was adapted to 4% (v/v) ethanol, and then subjected to UV mutagenesis. One respiration deficient mutant Rd-5 with improved xylose fermentation capability was selected. Protoplasts of Rd-5 were inactivated by UV treatment, followed by the PEG-mediated protoplast fusion with a Saccharomyces cerevisiae strain with good ethanol-fermenting capability. The xylose fermenting capability of the fusants was investigated, and the fusant F6 demonstrated good ethanol fermentation performance, producing 18.75 g•L-1 ethanol from 50 g•L-1 xylose with an ethanol yield of 0.375 or 73.4% of its theoretical value of 0.511. Comparing with its parent Candida shehatae strain, the ethanol yield of F6 was increased by 28%.