固定化基因重组酵母发酵木糖产乙醇

Ethanol fermentation on xylose by immobilized recombinant yeast

采用海藻酸钙凝胶包埋法固定基因重组酵母Sacchromyces cerevisiae ZU-10,研究了固定化细胞的发酵特性.结果表明,在30℃、pH 5.5下发酵80 g/L木糖,游离细胞的发酵周期为96 h,乙醇得率为0.37,细胞固定化后发酵周期缩短至60 h,乙醇得率提高到0.40.利用固定化细胞重复分批发酵8次,木糖利用率均在95%以上,平均乙醇得率为0.39.与游离细胞相比,固定化细胞对乙酸的耐受性明显增强,当质量浓度低于1.2 g/L时乙酸对木糖发酵的影响很小.利用固定化重组酵母发酵玉米秸秆水解液中的葡萄糖和木糖,36 h内65.0 g/L葡萄糖和27.0g/L木糖被完全利用,生成36.9 g/L乙醇,对葡萄糖和木糖的乙醇得率为0.40.

A recombinant yeast Sacchromyces cerevisiae ZU-10 was immobilized by calcium alginate gel entrapping method. Fermentation of 80 g/L xylose was carried out at 30 ℃, pH 5.5 by S. cerevisiae ZU-10. The period was shortened to 60 h and the ethanol yield was increased to 0.40 with immobilized cells compared with 96 h and 0.37 of free cells. During 8 repeated batches of ethanol fermentation by the immobilized cells, the xylose consumption yield exceeded 95% and the average ethanol yield reached 0.39. The immobilized cells showed enhanced tolerance to acetic acid, and lower than 1.2 g/L acetic acid in the culture medium caused little influence on xylose fermentation. During the fermentation of corn stalk hydrolysate for ethanol production, the immobilized cells completely consumed 65.0 g/L glucose and 27.0 g/L xylose within 36 h to yield 36.9 g/L ethanol, and the ethanol yield was 0.40 for glucose and xylose.