earticle

영어

One of the key issues in bioethanol production is a negative effect of ethanol on cell growth and ethanol production. In this study, the genes conferring ethanol tolerance on Sacchaomyces cerevisiae were identified through the yeast genomic library screening, and then the selected genes were used for strain development. By the screening of the S. cerevisiae S288C overexpression genomic library in a medium with 8% ethanol, the strains harboring each of PAU15, CMD1 and CIN5 genes were selected based on rapid growth rate relative to the control strain. In fed-batch fermentation in a media with 100 g/L glucose, however, overexpression of PAU15, CMD1, CIN5 did not improve ethanol production. To verify the reason for such inconsistency of the batch fermentation in 8% ethanol stress and the fed-batch fermentation, real-time PCR was performed. The transcriptional levels of the PAU15, CMD1 and CIN5 genes sharply increased during the early exponential phase, and then decreased in the stationary phase. The result implies that the PAU15, CMD1 and CIN5 gene products are not involved in the cell activity recovery in the gradual ethanol stress but effective in abrupt ethanol stress.