基于二次发酵酵母活力确定乙醇分批补料发酵最佳补料时间

Optimal Feeding Timing of Ethanol Fed-Batch Fermentation Based on Yeast Vitality of the Secondary Fermentation

摘要:

研究了二次发酵酵母活力以确定最佳补料时间，旨在为甘蔗糖蜜补料发酵提供研究基础。通过不同糖质量浓度乙醇分批发酵试验选择乙醇分批补料发酵最佳初糖质量浓度；然后将主发酵（初总糖220 g/L）不同时间点（0、6、12、18、24、30、36 h）取样酵母以相同细胞数接入二次发酵液中，通过分析二次发酵酵母的细胞活性、耗糖能力和乙醇生成能力，得到主发酵酵母活力最强的时间点；最后进行乙醇分批补料发酵验证试验。结果表明：二次发酵酵母活力强弱反映了所对应的主发酵取样时间点酵母活力，在二次发酵酵母发酵活力最强所对应的主发酵时间点（24 h）补料，主发酵效果最好；乙醇质量浓度为（136.62±1.10） g/L、乙醇产率为（2.53±0.02） g/（L·h）和总糖发酵效率为83.34%，说明二次发酵酵母活力可以作为确定乙醇发酵分批补料时间的指标。

Abstract:

To explore basic information for ethanol production from sugarcane molasses in fed-batch fermentation，yeast cell vitality of the secondary fermentation was investigated with aim at determining optimal feeding time based on the cell vitality. By batch fermentation at different initial sugar，optimal initial sugar concentration（220 g/L） for fed-batch fermentation was obtained. The secondary fermentations were done by inoculating the same amount of cells from the primary fermentation at 0，6，12，18，24，30，36 h，with emphasis on analyzing cell activity，sugar utilization and ethanol production for determining time point of highest cell vitality in the primary fermentation. By ethanol fed-batch fermentation with feeding timing based on cell vitality，the results showed that the optimum fermentation parameters were observed with feeding at 24 h when the cell vitality was the strongest，namely，the highest ethanol concentration（136.62±1.10） g/L，volumetric productivity（2.53±0.02） g/（L·h） and total sugar fermentation efficiency（83.34%） were achieved，indicating that the cell vitality of yeast based on secondary fermentation can be used as a parameter of feeding time in the ethanol fed-batch fermentation.