Abstract: A yeast strain S3 screened from the fruits was applied successfully to the close-circulating ethanol fermentation in the PDMS membrane bioreactor. Three parallel pure cultures in flakes were conducted for yeast strain S3. The max cell concentration, ethanol productivity and ethanol yield on glucose were 5.37 g/L, 1.90 g/L/h, 0.449g/g, respectively. With incubating S3 into the PDMS membrane bioreactor, the close-circulating ethanol fermentation was conducted, and the ferment experiment was steadily going on for 524.4h. The ethanol productivity was 1.48 g/L/h, and the glucose utilization 3.55 g/L/h. The yeast cell viability was still over 30% at the termination of fermentation. The ethanol yield on glucose was 0.416g/g, higher than that of strain S0 under similar ferment process. The ethanol yield on biomass and the specific ethanol formation rate of S3 through the ferment process were 77.63 g/g and 0.148 g/g/h, more 57% and 71% than those of S0, respectively. The experimental results indicated that strain S3 might be acclimatized and evolved to some extent in process of the close-circulating ethanol fermentation in the PDMS membrane bioreactor, and behave superior fermentation features to industrial Angel yeast strain S0.
