(291c) Probing the Toxicity of Ethanol to Biological Membranes with Application to Biofuels Production

Biological membranes form a barrier to protect the cell from its environment and consist of a wide variety of lipids. Most small molecules have very low permeability in biological membranes, but some are known to reside within regions of the membrane. In biofuels production, products and by products can be toxic to organisms making the fuel. These compounds can damage the cell membrane and lead to reduce function of the cell or even death. Our objective is to systematically probe the effects of ethanol on various lipid bilayers at concentration levels from 0.5-4mol% (on a water-only basis). Lipid head groups that are common to the plasma membrane of yeast were simulated with 1-palmitoyl-2-oleoyl (PO) chains: phosphoethanolamine (PE), phosphatidylcholine (PC), and phosphoserine (PS). The penetration of ethanol and its interaction with these lipid membranes depends on the type of head group (zwitterionic vs. anionic). Ethanol is found to expand the lipid bilayer and thus increasing its overall permeability. Future work will involve studies on realistic yeast membrane models and determining what lipids might reduce the toxic effects of ethanol to yeast.