Influence of unsaturated fatty acids, membrane fluidity and oxygenation on the survival of an E. coli fatty acid auxotroph following gamma-irradiation.

Escherichia coli K1060, a fatty acid auxotroph unable to either synthesize or degrade unsaturated fatty acids (uFAs), was used to study the effect of membrane fluidity on survival after exposure to ionizing radiation. Using this strain of E. coli, significant alterations in the fatty acid composition of the membrane have been produced and verified by gas chromatography. Linolenic, oleic, elaidic and palmitelaidic acids were the uFAs used. Survival above the transition temperature (Tt) (liquid crystal in equilibrium gel) was comparable for these fatty-acid-supplemented membranes after exposure to gamma-irradiation, whereas gamma-irradiation below Tt resulted ina significant decrease in survival. An oxygen enhancement effect was observed for each experimental condition employed.