Abstract: Continuous ethanol fermentation coupled with the recycling of waste distillage was carried out in a single agitating bioreactor with the self-flocculating yeast and two-stage enzymatic hydrolysate of corn meal. The fermentation broth collected was distilled to separate ethanol and other volatile products in every 3 d, and the distillage was used to mix corn meal instead of fresh water. The fermentation system was run continuously for 25 d, and the accumulation of acetic acid, lactic acid, propionic acid, furfural and 2-phenyl-ethyl-alcohol, the byproducts that are inhibitory in the growth and ethanol fermentation of the self-flocculating yeast with their minimum inhibition concentrations of 3, 20, 1.5, 2 and 1.5 g/L, respectively, was monitored. It was found that propionic acid with its concentration of 2.7 g/L was the only byproduct accumulated to the level higher than its minimum inhibition concentration. And in the meantime, the synergistic effect of propionic acid and 2-phenyl-ethyl-alcohol as well as furfural and 2-phenyl-ethyl-alcohol were observed.

Key words: self-flocculating yeast, waste distillage recycling, continuous ethanol fermentation, byproduct inhibition

摘要： 在单级搅拌式生物反应器中，以双酶法制备的玉米糖化液为底物，进行了废糟液全循环条件下自絮凝颗粒酵母乙醇连续发酵实验. 每隔3 d将收集到的发酵液集中精馏处理，得到的废糟液直接用于玉米粉调浆. 实验装置连续运行25 d. 结果表明，乙酸、乳酸、丙酸、糠醛和2-苯乙醇随废糟液循环不断积累，其中丙酸积累最明显，浓度可达2.7 g/L，是唯一超过临界抑制浓度的副产物. 通过摇瓶添加实验测得上述5种副产物对酵母细胞生长和乙醇发酵的最小抑制浓度分别为3, 20, 1.5, 2和1.5 g/L，丙酸与2-苯乙醇及糠醛与2-苯乙醇之间的协同效应最强.

关键词: 自絮凝酵母, 废液全循环, 乙醇连续发酵, 副产物抑制效应