MEMBRANE LIPID AND STEROL DISTRIBUTION IN SACCHAROMYCES-BAYANUS

Vaseline oil and sunflower oil are used as antifoam agents in industri al fermentations; a mixture of mono- and diglycerides is also often em ployed as an emulsifier in biotechnological processes. The presence in the medium of the two oils at a concentration of 0.2% leads to a decr ease in biomass of 7%, with a slight but constant decrease of viabilit y. The presence of the mono- and diglyceride mixture had no significan t effect. All the products modified the plasma membrane lipid composit ion. The total fatty acid content was increased but the levels of unsa turated derivatives remained constant with Vaseline oil, and was sligh tly enhanced with all the acylglycerol products. The content of total sterols was also increased by culture of the cells with all the produc ts. However, although the percentages of ergosterol were diminished, t hose of some intermediates in ergosterol synthesis were significantly enhanced.