• Journal of Life Science
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• v.26 no.1
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• pp.17-22
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• 2016

Ethanol is a very valuable material, however, it is also a source of stress, as the accumulation of ethanol in a medium inhibits cell viability and decreases productivity of the target product. Therefore, the ethanol tolerance of yeast, which is closely related to ethanol productivity, is an important factor in industrial ethanol production. In this study, the YDJ1 and PEP5 genes were selected as target genes for elucidating ethanol-tolerant mechanisms by analyzing the expression regulation of these genes. The pA-YDJ1 and pA-PEP5 plasmids containing YDJ1 and PEP5 genes under an ADH1 promoter, respectively, were constructed and transformed into BY4742 (host strain), BY4742△ydj1, and BY4742△pep5 strains. The ethanol tolerance in the BY4742△ydj1/ pA-YDJ1 and BY4742△pep5/pA-PEP5 transformants was restored by overexpression of the YDJ1 and PEP5 genes to the host strain level. The YDJ1 and PEP5 genes were also introduced into the double gene disruptant (BY4742△ydj1△pep5) to investigate the expression regulation of the YDJ1 and PEP5 genes. The simultaneous overexpression of the YDJ1 and PEP5 genes restored ethanol tolerance to the 90% level of the BY4742 strain under 8% ethanol stress. The YDJ1 gene induced more overexpression of the PEP5 gene in the BY4742△ydj1 △pep5/pA-YDJ1, pA-PEP5 strain, suggesting that the YDJ1 gene partially regulates the expression of the PEP5 gene as an upstream regulator.