Phosphatidylinositol (PI)

Phosphatidylinositol is a negatively charged phospholipid and a minor component in the cytosolic side of eukaryotic cell membranes.The inositol can be phosphorylated to form phosphatidylinositol phosphate (PIP), phosphatidylinositol bisphosphate (PIP₂) and phosphatidylinositol trisphosphate (PIP₃). With inositol in the fermentation medium, phosphatidylinositol (PI) content was increased, while phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were decreased. When yeast cells had a higher content of PI, they produced ethanol much more rapidly and tolerated higher concentrations of ethanol. During ethanol shock treatment at 18% (v/v) ethanol, yeast cells with a higher concentration of PI lost their viability much more slowly than those with a lower concentration of PI, indicating that the PI content in these yeast cells can play an important role in ethanol production and ethanol tolerance.