Improvement of Ethanol Tolerance by Inactive Protoplast Fusion inSaccharomyces cerevisiae

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, SO2 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.

Co-Fermentation of Glucose–Xylose–Cellobiose–XOS Mixtures Using a Synthetic Consortium of Recombinant Saccharomyces cerevisiae Strains

“…Since the synthetic S. cerevisiae consortium used in this work contained two haploid yeast strains, it is essential to obtain the corresponding diploid or polyploid progeny to efficiently consume all the LB-derived sugars in the presence of various inhibitory factors. To this end, traditional protoplast fusion [73], iHyPr, or the CRISPR/Cas9-mediated method could be used in our future work.…”

Strategies for the Development of Industrial Fungal Producing Strains

“…The fusants produced ethanol directly from cellulosic materials [75]. Additionally, improvement has been reported for the fusion between the strain S. cerevisiae Q, frequently used as a beer producer, with S. cerevisiae L. The fusant showed higher ethanol tolerance (14% v/v) than the strain Q (10% v/v) [68]. The protoplast fusion of S. cerevisiae and C. shehatae followed by UV mutagenesis resulted in an increase of ethanol production at 42 • C, with 90% fermentation efficiency [76].…”

Breeding of high‐tolerance yeast by adaptive evolution and high‐gravity brewing of mutant

“…Generally, breeding mutants with high tolerance is one of the most commonly used methods. The primary approaches to enhance ethanol tolerance in S. cerevisiae include adaptive laboratory evolution (ALE), 16 mutagenesis, 17 protoplast fusion 18 and gene manipulation through techniques such as genome editing, 19 metabolic engineering 20 and targeted gene expression modulation 21 . Among them, ALE has the advantage of allowing the regulation of many different genes in parallel without a decrease in cellular fitness.…”