Alcohol tolerance in Escherichia coli.

During growth with ethanol, the proportion of 18:1 fatty acid in the lipids of E. coli increases at the expense of saturated fatty acids. The significance of these changes was investigated in terms of growth and survival in the presence of ethanol. Two approaches were used: (1) A comparison of alcohol tolerance among strains of E. coli with different fatty acid compositions; (2) A comparison of alcohol tolerance using a lipid mutant in which the fatty acid composition was controlled by exogenous supplements. An increase in unsaturated fatty acid content was beneficial for both growth and survival. We conclude that the alcohol-induced changes in the fatty acid composition of E. coli are part of an adaptive response, compensating for some of the harmful effects of this drug.