Biological membranes and methods for their characterization - current approach.

Cell membrane of prokaryotes is immediately exposed to various environmental changes. To survive, the organism has to sufficiently react to these changes and adapt to them. On the level of the lipid bilayer it means changes of membrane fluidity induced by alterations of the lipid composition. Even a small alteration of acyl chains or polar heads of the phospholipids can alter the order of the lipid bilayer. Various biophysical techniques have been used to detect changes of the membrane fluidity and lipid composition. The purpose of this work is to summarize mechanism of adaptation induced by cold, heat and osmotic shock, as well as commonly used methods for detection of these changes. Studied organisms represent Gram- negative Escherichia coli and Gram-positive Bacillus subtilis. Key words biological membranes, membrane fluidity, adaptation of prokaryotic organisms to environmental changes, methods of characterization of biological membranes, membrane spectroscop