Improvement of Ethanol Tolerance by Inactive Protoplast Fusion in <i>Saccharomyces cerevisiae</i>
Xin Yi, Mei Yang, Hua Yin, Jianming Yang
Abstract
Saccharomyces cerevisiae is a typical fermentation yeast in beer production. Improving ethanol tolerance of S. cerevisiae will increase fermentation efficiency, thereby reducing capital costs. Here, we found that S. cerevisiae strain L exhibited a higher ethanol tolerance (14%, v/v) than the fermentative strain Q (10%, v/v). In order to enhance the strain Q ethanol tolerance but preserve its fermentation property, protoplast fusion was performed with haploids from strain Q and L. The fusant Q/L‐f2 with 14% ethanol tolerance was obtained. Meanwhile, the fermentation properties (flocculability, SO 2 production, α ‐N assimilation rate, GSH production, etc.) of Q/L‐f2 were similar to those of strain Q. Therefore, our works established a series of high ethanol‐tolerant strains in beer production. Moreover, this demonstration of inactivated protoplast fusion in industrial S. cerevisiae strain opens many doors for yeast‐based biotechnological applications.