Effect of overexpression of transcription factors on the fermentation properties ofSaccharomyces cerevisiaeindustrial strains

To investigate the effect of modulation of transcription factors on the fermentation properties of Saccharomyces cerevisiae industrial strains and to evaluate whether overexpression and co-overexpression of transcription factors would result in higher ethanol yield.A mutant gene spt15 (Phe(177)Ser, Tyr(195)His, Lys(218)Arg) was constructed by polymerase chain reaction mediated site-directed mutagenesis. The fermentation properties of the engineered strains in very high gravity fermentations were investigated. It is found that overexpression of SPT3 can enhance the resistance to ethanol and osmotic stress. On the contrary, overexpression of SPT15 or spt15 cannot obviously improve osmotic and ethanol tolerance of industrial strains. Additionally, simultaneous overexpression of SPT15 and SPT3 can not only distinctly enhance the resistance to ethanol and osmotic stress, but also improve fermentation performance.Simultaneous modulation of the expression level of SPT15 and SPT3 can increase the production of ethanol by improving osmotic tolerance and ethanol tolerance of industrial strains.Modulation of transcription factors provides a route to fermentation phenotypes of industrial yeast strains that are not readily accessible by traditional methods.