外源乙醇对果糖与葡萄糖酒精发酵的影响

研究了不同体积分数外源乙醇对酵母GJ2008利用等量果糖与葡萄糖混合发酵过程的影响,旨在为高浓度甘蔗汁酒精发酵提供参考和依据。用YPDF培养基模拟甘蔗汁,并调节乙醇体积分数为0%、6%、9%和12%,以初始酵母数为1.12×108个/mL进行酒精发酵,高效液相色谱法测定发酵过程中果糖与葡萄糖含量,并采用曲线下面积法对果糖与葡萄糖代谢曲线进行分析。在外源乙醇体积分数为0%~9%时,酵母GJ2008可以快速利用果糖和葡萄糖进行酒精发酵,但对葡萄糖有着明显的偏好;在外源乙醇体积分数为12%时,果糖和葡萄糖消耗缓慢,生物量得不到有效增加。等质量浓度果糖与葡萄糖混合发酵表明:外源乙醇对果糖代谢的影响明显大于对葡萄糖代谢的影响,外源乙醇体积分数达6%以上时,糖转化乙醇的产量减少了19%~27%。

Influence of External Ethanol Additions on Fructose and Glucose Fermentations by Saccharomyces cerevisiae

To provide basic information for high gravity sugarcane fermentation, external ethanol was added to evaluate its impact on fructose and glucose fermentations by S.cerevisiae GJ2008. YPDF medium was used to simulate sugarcane juice to carry out ethanol fermentation at four different external ethanol concentrations ranging from 0% to 12% with an initial yeast number of 1.12×108 cells/mL, and the contents of fructose and glucose were determined by HPLC(High Performance Liquid Chromatography). Area under the curve (AUC) of fermentation of fructose and glucose was obtained using GraphPad Prism 5 software to analyze the discrepancy in fructose and glucose consumption. External ethanol addition had an important impact on fructose and glucose consumption, S.cerevisiae GJ2008 could utilize both sugars rapidly at the external ethanol concentration of less than 9% but with an obvious preference for glucose. Consumption of both sugars was severely inhibited when the external ethanol concentration increased up to about 12%, and the biomass could not be effectively produced. Fructose utilization was inhibited to a larger extent than glucose by external ethanol addition. The ethanol production was reduced by 19%~27% after the addition of external ethanol higher than 6%.