树干毕赤酵母和酿酒酵母混合糖发酵产乙醇

以树干毕赤酵母和酿酒酵母为发酵菌株,酸性蒸汽爆破玉米秸秆预水解液和纯糖模拟液为C源,采用固定化酵母细胞的方法,研究了酸爆玉米秸秆预水解液初始pH、N源种类及其浓度、3种发酵模式对树干毕赤酵母戊糖发酵的影响。结果表明:玉米秸秆预水解液适合发酵的初始pH范围为6.0～7.0;1.0 g/L的(NH4)2SO4作为N源,在40 g/L葡萄糖和25 g/L木糖培养基中发酵24 h,糖利用率达到99.47%,乙醇质量浓度为24.72 g/L,优于尿素和蛋白胨作为N源;3种模式的发酵体系中,以游离树干毕赤酵母和固定化酿酒酵母发酵性能最好,糖利用率和乙醇得率分别为99.43%和96.39%。

Co-fermentation of mixture of glucose and xylose to ethanol by Pichia stipitis and Saccharomyces cerevisiae

Acid steam explosion pre-hydrolysis of corn stalk and pure sugar analog fluid fermented by Pichia stipites and Saccharomyces cerevisiae. The effects of initial pH of pre-hydrolysis of corn stalk, the effect of type and concentration of nitrogen and three fermentation patterns on fermentation of P. stipites were studied. The result showed that the initial pH range of pre-hydrolysis of corn stalk for fermentation was pH 6.0 to pH 7.0. 1.0g/L （ NH4 ） 2SO4 was used as the nitrogen source, in 40 g/L glucose and 25 g/L xylose fermentation medium for 24 h, and sugar utilization was 99.47%, ethanol concentration was 24.72 g/L, which was superior to urea and peptone as nitrogen source. Fermentation performances of free P. stipitis cell and immobilized S. cerevisiae were the best, sugar utilization and ethanol yield were 99.43%, and 96. 39%. Immobilized yeast could achieve high-density fermentation, thus improving equipment utilization and having a better prospect on multi-stage continuous fermentation in the bioreactor.