外部因素对酒精酵母GJ2008果糖与葡萄糖酒精发酵的影响

Influence of External Factors on Fructose and Glucose Fermentations by Saccharomyces cerevisiae GJ2008

DOI：10.3969/j.issn.1673-1689.2015.07.015

中文关键词: 糖比例 果糖 葡萄糖 微通氧 酒精发酵

英文关键词: hexose ratio, fructose, glucose, micro-aeration, ethanol fermentation

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中文摘要:

在高体积分数乙醇胁迫下，考察糖比例、微通氧和温度等外部因素对果糖与葡萄糖利用及其差异性的影响，旨在为高浓度甘蔗汁发酵生产酒精提供参考和依据。用YPDF培养基模拟甘蔗汁，调节乙醇体积分数为11.2%，初始酵母数为1.40×108个/mL进行酒精发酵，测定发酵过程中果糖与葡萄糖质量分数，并采用曲线下面积法对果糖与葡萄糖代谢曲线进行分析。在高体积分数乙醇胁迫条件下，葡萄糖质量分数占初总糖质量分数40%及以上时，果糖代谢会严重地受到葡萄糖的代谢阻遏；微通氧可有效地缩小发酵后期果糖/葡萄糖利用差异性，提高乙醇产率61.70%；较低温度明显有利于发酵后期酵母数的维持；相比外源乙醇，糖的代谢更易受到内源乙醇的影响。酒精酵母GJ2008对葡萄糖有一定偏好性，然而此种偏好性不会受到外部因素的影响。对高体积分数甘蔗汁酒精发酵而言，发酵后期需保证微通氧和较低温环境，并应尽可能减少发酵后期葡萄糖的含量，从而去除葡萄糖对果糖的代谢调控作用。

英文摘要:

The external factors affecting the differences between fructose and glucose consumptions and fermentations under high concentrations of ethanol were investigated by the effects of hexose ratio，micro-aeration and temperature to provide basis for the alcoholic fermentation of high gravity sugarcane juice. Sugarcane juice was simulated using YPDF medium and fermented under ethanol concentration of 11.2% (v/v) and with an initial yeast number of 1.40×108 cells/mL. The concentrations of fructose and glucose in the process of fermentation were determined by HPLC. Metabolic curves of fructose and glucose fermentation were analyzed and fitted by the area under the curve (AUC) method. The fructose metabolism was seriously impeded by the glucose metabolism under high concentrations of ethanol if the initial glucose was more than 40% of total sugar. Micro-aeration could effectively reduce the differences between fructose and glucose consumptions during the late stages of the fermentation，and the ethanol productivity was raised by 61.70%. Low temperature was apparently favorable to maintain the final biomass，while sugar metabolism was susceptible to the endogenous ethanol rather than the exogenous ethanol. In addition，there was a preference to glucose for S.cerevisiae GJ2008，however，the preference was not affected by the environmental factors. For the alcoholic fermentation of high gravity sugarcane juice，it is recommended to maintain a micro-aeration and a low temperature condition during the late stages of the fermentation，in which stages the glucose concentration should be well reduced to remove its metabolic repression to fructose.

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