Abstract:

In the present study, the effects of several fatty acids on the ethanol tolerance of Saccharomyces cerevisiae were
evaluated by cell survival rate, growth rate and fermentation ability. The results showed that the survival rate of S. cerevisiae
under alcohol shock was significantly increased by the addition of two unsaturated fatty acids (palmitoleic acid and oleic
acid) in the culture medium, while palmitoleic acid was more effective than oleic acid. The survival yeasts also grew faster
in the medium containing alcohol. The two saturated fatty acids palmitic acid and stearic acid made no contribution to
promoting the survival rate and growth rate of S. cerevisiae. On the other hand, with the same concentration of unsaturated
fatty acids, yeasts cultured to the stationary phase displayed higher survival rate and faster growth rate compared with the
exponential phase. However, yeasts cultured with short-chain fatty acids (palmitoleic acid and palmitic acid) achieved
high alcohol content. The ethanol tolerance results during fermentation were inconsistent with the growth results. Thus the
mechanism of ethanol tolerance of S. cerevisiae is different from that of cell growth during fermentation.

Key words: Saccharomyces cerevisiae, fatty acids, ethanol tolerance, growth, fermentation