Membrane lipid and sterol distribution in Saccharomyces bayanus

Abstract Vaseline oil and sunflower oil are used as antifoam agents in industrial fermantations; a mixture of mono- and diglycerides is also often employed as an emulsifier in biotechnological processes. The presence in the medium of the two oils at a concentration of 0.2% leads to a decrease in biomass of 7%, with a slight but constant decrease of viability. The presence of the mono- and diglyceride mixture had no significant effect. All the products modified the plasma membrane lipid composition. The total fatty acid content was increased but the levels of unsaturated derivatives remained constant with Vaseline oil, and was slightly enhanced with all the acylglycerol products. The content of total sterols was also increased by culture of the cells with all the products. However, although the percentages of ergosterol were diminished, those of some intermediates in ergosterol synthesis were significantly enhanced.