Adaptation of lipid membranes of yeast to high ethanol media

WILKE, NATALIA; CROSIO, MATIAS; GENOVESE, DARIO; DOMINI, GEORGINA; SCARZELLO, FACUNDO

Rosario, Santa Fe

Congreso; L Reunión Anual SAB; 2022

Asociación Argentina de Biofísica (SAB)

Some yeasts used in industrial fermentation processes such as wine or beer production,have the ability to resist high ethanol concentrations. This phenomenon generates interestin understanding what processes allow them to resist these stressful conditions, and it hasbeen postulated that lipid composition of the cell membranes are especially important inthe acclimation of yeast to ethanol stress. These composition changes may lead tochanges in membrane biophysical properties.Several studies have been carried out related to changes in the chemical composition ofthe membranes of yeast subjected to exogenous ethanol, but the changes in theirbiophysical properties have been less characterized.Therefore, our aim is to understand which physical properties of the membranes changeand 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 highethanol content (acclimated yeasts), and membranes prepared with these extracts werecharacterized. We tested the fluorescence of the probe Laurdan, the behavior of Langmuirmonolayers upon compression and the conductivity in the presence and in the absence of15% v/v of ethanol.We found that the fluorescence emission of laurdan was different in liposomes composedof the two extracts, being the GP = 0.3 for yeast grown in rich media and 1.5 times largerfor yeast grown in the presence of ethanol. The compressibility of Langmuir monolayerswas similar between the extracts, but the surface potential was significantly lower formonolayers prepared with extracts of acclimated yeasts. Finally, regarding bilayerconductivity, extracts from acclimated cells appear to have lower values, but datadispersion is too high and more experiments have to be performed.The results obtained suggest that the lipid bilayers of yeast adopt higher structure ofwater and a less permeable structure when the cells are grown in media with ethanol.