Combined effects of ethanol, high homogenization pressure, and temperature on cell fatty acid composition in Saccharomyces cerevisiae

The specific aims of this research were to evaluate the combined effects of ethanol and high-pressure homogenization at different temperatures on cell viability in Saccharomyces cerevisiae and to study the induced modification of fatty acid composition. The decrease in viability was weak at 10 degrees C while a homogenization pressure over 1000 bar (1 bar = 100 kPa) induced a significant reduction in viability when the cells were incubated at 20 and 30 degrees C. The cell tolerance to pressure decreased with an increase in ethanol concentration and temperature. Ethanol, particularly intracellular ethanol accumulated by S. cerevisiae, played an important role in the response to homogenization pressure and in modification of the cell fatty acid composition. In fact, an unusually elevated accumulation of ethyl esters in lipid extracts of yeast cells subjected to high homogenization pressure, especially in the presence of exogenous ethanol and at 30 degrees C, was observed. Moreover, only unsaturated and traces of short chain fatty acids were esterified with ethanol.