废糟液全循环条件下絮凝酵母乙醇连续发酵  

Process development for continuous ethanol fermentation by the flocculating yeast under stillage backset conditions

作　　者：孜力汗[1] 刘晨光[1] 白凤武[1] 

机构地区：[1]大连理工大学生命科学与技术学院,辽宁大连116024

出　　处：《生物工程学报》2014年第2期310-314,共5页Chinese Journal of Biotechnology

基　　金：国家高科技研究发展计划(863计划)(No.2012AA021205);国家国际科技合作专项(No.2013DFA60470)资助~~

摘　　要：丙酸是以玉米为原料自絮凝酵母乙醇连续发酵系统废糟液全循环过程中积累的主要抑制物。基于丙酸对酵母细胞抑制机理,开发了3种废糟液全循环条件下乙醇连续发酵工艺策略。首先根据高温导致丙酸生成的现象,去除了物料灭菌环节,使发酵液丙酸浓度显著降低,生物量和乙醇浓度分别提高了59.3%和7.4%。其次,以丙酸浓度达到半数抑制浓度(IC50)40 mmol/L为目标,通过拟合丙酸积累数据预测废糟液全循环的最长运行时间,发酵装置运行应控制在此时间范围内。再次,较低的环境pH值提高了丙酸毒性,而实验证明发酵液pH为5.5时,丙酸对细胞生长的抑制影响最小,因此控制发酵过程中的pH有利于弱化丙酸毒性。Propionic acid, a major inhibitor to yeast cells, was accumulated during continuous ethanol fermentation from corn meal hydrolysate by the flocculating yeast under stillage backset conditions. Based on its inhibition mechanism in yeast cells, strategies were developed for alleviating this effect. Firstly, high temperature processes such as medium sterilization generated more propionic acid, which should be avoided. Propionic acid was reduced significantly during ethanol fermentation without medium sterilization, and concentrations of biomass and ethanol increased by 59.3% and 7.4%, respectively. Secondly, the running time of stillage backset should be controlled so that propionic acid accumulated would be lower than its half inhibition concentration IC50 （40 mmol/L）. Finally, because low pH augmented propionic acid inhibition in yeast cells, a higher pH of 5.5 was validated to be suitable for ethanol fermentation under the stillage backset condition.

关 键 词：自絮凝酵母 乙醇连续发酵 废糟液全循环 丙酸抑制 

分 类 号：TQ223.122[化学工程—有机化工]