应用硅橡胶膜生物反应器的发酵-渗透汽化耦合功能,进行长期封闭循环发酵,使酵母在这种特定环境下完成适应性自然进化,从而获得优势的突变株。以工业安琪酵母ADY为原始菌株,进行每一轮500h的封闭循环发酵,在发酵终点取菌悬液做平板筛菌,分离出遗传约200代的相对强势的新菌株,再转移新菌株进行同样的发酵和终点筛选实验。如此的发酵-筛选-转移实验共进行了3轮。试验结果表明:ADY遗传超过600代的菌株S33,在500h封闭循环发酵残液配制的培养基条件下,表现出了明显的环境适应性遗传优势,其细胞生长速率、产物乙醇的比生成速率和糖转化率都相对原种菌ADY分别提高了约71.8%、53.6%和52.7%。

A Saccharomyces cerevisiae could be acclimated and evolved by a long continuous and close circulation fermentation in the PDMS membrane bioreactor system which coupled the fermentation with pervaporation,and a superior mutant strain could be obtained.In this work,Angel yeast(ADY) was taken as the parent strain and underwent a continuous and close circulation fermentation of 500 h.At termination of the fermentation,as a descendant of 200 generations of ADY,a preferable strain was screened from the residual broth by a usual method.The screened strain was transferred and inoculated into next fermentation and the same screening was conducted as previous fermentation.The fermentation-screening-transfer procedure was repeated three times until a 600-generation descendant was screened.The strain S33 from the third run was showing great superiority over ADY under a substrate prepared by the residual broth after 500 h fermentation,with the cell growth rate,ethanol yield rate and glucose conversion percent increased by 71.8%,53.6% and 52.7% respectively.