稳定代谢葡萄糖和木糖产乙醇的重组酿酒酵母工程菌初步构建

Construction of Engineered Saccharomyces cerevisiae for Steadily Metabolizing Glucose and Xylose to Ethanol

分别克隆了休哈塔假丝酵母(Candida shehatae)的木糖还原酶基因XYL1和热带假丝酵母(Candida tropicalis)的木糖醇脱氢酶基因XYL2,构建出重组表达质粒pACT2-xyl1和pDR195-xyl2,并使其分别转化酿酒酵母受体细胞.酶活测定结果显示,转化子中木糖还原酶和木糖醇脱氢酶均在宿主菌中得到活性表达.并将这两个基因连同各自重组表达质粒上的表达元件进行了克隆,进而构建出重组酵母染色体整合质粒YIp5-kanR-x12,以期今后通过同源重组的原理将上述基因整合到发酵性能良好的酿酒酵母基因组中,得到稳定代谢葡萄糖和木糖产乙醇的重组酵母菌株.

This paper presents our studies on the cloning of gene XYL1 encoding xylose reductase （XR） from Candida shehatae and gene XYL2 encoding xylitol dehydrogenase （XDH） from Candida tropicalis, the establishment of recombinant expression plasmids pACT2-xyl1 and pDR195-xyl2. The two plasmids were used to transform the Saccharomyces cerevisiae host cell, respectively. The specific enzyme activities indicated that both the XR and XDH were functionally expressed in the host cell. The two genes and their expression elements were cloned from the recombinant expression plasmids to construct recombinant plasmid YIp5-kanR-x12 afterwards. It is expected that the above genes could be integrated into the genome of S. cerevisiae possessing good fermentation abilities by homologous recombination to acquire a recombinant yeast strain that could metabolize glucose and xylose to ethanol steadily. Fig 3, Tab1, Ref 15