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Saccharomyces cerevisiae (S. cerevisiae) is the main fermentation strain in brewing industry. However, the accumulation of ethanol during the fermentation inhibits the growth of S. cerevisiae. Polyphenols are important bioactive ingredients in oolong tea, and epigallocatechin-3-O-(3"-O-methyl)-gallate (EGCG3"Me) has exhibited ameliorate effect on alcohol intoxication. Therefore, in the current work, we used RNA-seq transcriptomics and iTRAQ proteomic analysis to study the effect of EGCG3"Me on ethanol-stressed S. cerevisiae. After EGCG3"Me intervention (0.8%, w/v), 178 up-regulated and 172 down-regulated genes were identified, meanwhile, 190 differentially expressed proteins (DEPs) were identified. In addition, KEGG pathways for metabolic pathways, biosynthesis of secondary metabolites and microbial metabolism were among the most DEPs after EGCG3"Me intervention. The integrated transcriptomic and proteomic analysis indicated EGCG3"Me may alleviate ethanol-induced damage on the cell wall and cell membrane of S. cerevisiae, and facilitate the redox balance and glycolysis. This study provides new insights into the mechanisms underlying the molecular response to ethanol in S. cerevisiae by the treatment of EGCG3"Me., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Saccharomyces cerevisiae has been widely used to produce alcoholic beverages and bio-fuels; however, its performance is remarkably compromised by the increased ethanol concentration during the fermentation process. In this study, RNA-sequence analysis was used to investigate the protective effect of green tea polyphenols (GTP) on S. cerevisiae cells from ethanol-induced damage. GO and KEGG analysis showed that to deal with the stress of ethanol, large amounts of genes related to cell wall, cell membrane, basic metabolism and redox regulation were significantly differentially expressed (P < 0.05), while these undesired changes could be partly relieved by administration of GTP, suggesting its potential to enhance the ethanol tolerance of S. cerevisiae. The present study provided a global view of the transcriptomic changes of S. cerevisiae in response to the accumulation of ethanol and the treatment of GTP, which might deepen our understanding about S. cerevisiae and the fermentation process, and thus benefit the development of the bioethanol production industry.

Saccharomyces cerevisiae (S. cerevisiae) plays a critical role in ethanol fermentation. However, during the fermentation, yeast cells are exposed to the accumulation of ethanol, which significantly affect the cell growth and the target product yield. In the present work, we employed RNA-sequence (RNA-seq) to investigate the ameliorate effect of Cyclocarya paliurus (C. paliurus) triterpenoids on S. cerevisiae under the ethanol stress. After C. paliurus triterpenoids intervention (0.3% v/v), 84 differentially expressed genes (DEGs) were identified, including 39 up-regulated and 45 down-regulated genes. The addition of triterpenoids decreased the filamentous and invasive growth of cells, and benefit to the redox balance and glycolysis. This study offers a global view through transcriptome analysis to understand the molecular response to ethanol in Sc131 by the treatment of C. paliurus triterpenoids, which may be helpful to enhance ethanol tolerance of S. cerevisiae in the fermentation of Chinese fruit wine.

The biggest challenge of utilizing lignocellulosic feedstocks for efficient ethanol fermentation is to improve strains and processes capable of mixed sugar fermentation in the presence of released inhibitors. A previously reported Saccharomyces cerevisiae strain WXY70 was further engineered to overexpress up to eight xylose metabolic genes or a transcription factor SPT2 , and their efficacy in fermentation was evaluated in a simulated corn hydrolysate, resulting in two favored strains 8G-3 and SPT2OE. SPT2OE produced 0.503 and 0.508 g ethanol/g total sugars in ball milling-based and corn hydrolysates, respectively, within 24 h. Moreover, SPT2OE produced about 40 g/L ethanol from 120 g/L xylose mother liquid solution. Overall, the fermentation performance of SPT2 overexpression was superior to recently reported SFA1 overexpression and achieved promising results of ethanol yield and titer in different hydrolysates. [Display omitted] • 8G-3 consumed 111.9 g/L xylose and produced 40.9 g/L ethanol. • SPT2OE utilized 107.2 g/L xylose and produced 40.7 g/L ethanol. • Both strains reached ethanol theoretical maximum. • SPT2OE rapidly achieved 70.7 g/L ethanol in hydrolysate. [ABSTRACT FROM AUTHOR]