Adaptation of lipid membranes of yeast to high ethanol media

N. WILKE,; CROSIO, M; D. GENOVESE; DOMINI GEORGINA; SCARZELLO FACUNDO

Rosario

Congreso; L Reunión Anual SAB; 2022

Some yeasts used in industrial fermentation processes such as wine or beer production, have the ability to resist high ethanol concentrations. This phenomenon generates interest in understanding what processes allow them to resist these stressful conditions, and it has been postulated that lipid composition of the cell membranes are especially important in the acclimation of yeast to ethanol stress. These composition changes may lead to changes in membrane biophysical properties.Several studies have been carried out related to changes in the chemical composition of the membranes of yeast subjected to exogenous ethanol, but the changes in their biophysical properties have been less characterized.Therefore, our aim is to understand which physical properties of the membranes change and how it changes when yeasts acclimate to high concentrations of ethanol. For this end, total lipids were extracted from BY4741 yeasts grown in rich media without or with high ethanol content (acclimated yeasts), and membranes prepared with these extracts were characterized. We tested the fluorescence of the probe Laurdan, the behavior of Langmuir monolayers upon compression and the conductivity in the presence and in the absence of 15% v/v of ethanol.We found that the fluorescence emission of laurdan was different in liposomes composed of the two extracts, being the GP = 0.3 for yeast grown in rich media and 1.5 times larger for yeast grown in the presence of ethanol. The compressibility of Langmuir monolayers was similar between the extracts, but the surface potential was significantly lower for monolayers prepared with extracts of acclimated yeasts. Finally, regarding bilayer conductivity, extracts from acclimated cells appear to have lower values, but data dispersion is too high and more experiments have to be performed.The results obtained suggest that the lipid bilayers of yeast adopt higher structure of water and a less permeable structure when the cells are grown in media with ethanol.