Role of phosphatidylinositol (PI) in ethanol production and ethanol tolerance by a high ethanol producing yeast

The effect of inositol addition on phospholipids, cell growth, ethanol prod uction and ethanol tolerance in a high ethanol producing Saccharomyces sp w ere studied. Addition of inositol greatly influenced major phospholipid syn thesis. With inositol in the fermentation medium, phosphatidylinositol (PI) content was increased, while phosphatidylcholine (PC) and phosphatidyletha nolamine (PE) were decreased. However, without inositol in the fermentation medium, PI content dropped down within 24 h, then increased, but was lower than in the presence of inositol. When yeast cells had a higher content of PI, they produced ethanol much more rapidly and tolerated higher concentra tions of ethanol, During ethanol shock treatment at 18%; (v/v) ethanol, yea st cells with a higher concentration of Pt lost their viability much more s lowly than those with a lower concentration of PI, indicating that the PI c ontent in these yeast cells can play an important role in ethanol productio n and ethanol tolerance. Fatty acids and ergosterol were not responsible fo r high ethanol tolerance and high ethanol production in this yeast strain.