Pseudomonas putidaNCTC 10936 Balances Membrane Fluidity in Response to Physical and Chemical Stress by Changing the Saturation Degree and the Trans/cisRatio of Fatty Acids

This study explored the capability of Pseudomonas putidaNCTC 10936 to maintain homeoviscosity after changing the growth temperature, incubating resting cells at different temperatures or at a constant temperature in the presence of 4-chlorophenol (4-CP). After raising the growth temperature from 20 to either 30 or 35°C, the degree of saturation of the organism’s fatty acids increased and the ratio of transto cisunsaturated fatty acids decreased somewhat. In contrast, after the incubation temperature of resting cells was raised (grown at 30°C) from 20 to 30 or 35°C the degree of saturation of the fatty acids remained nearly constant, while the ratio of transto cisunsaturated fatty acids increased. Incubating resting cells (grown at 30°C) at 20°C in the presence of 4-CP again caused no major changes in the degree of saturation, but cisto transconversion of unsaturated fatty acids was induced, with a corresponding increase in the trans/cisratios. Increases in both the saturation degree of the fatty acids and the trans/cisratio of the unsaturated fatty acids correlated with increases in the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene intercalated in the bilayers of liposomes prepared from the cells of P. putidaNCTC 10936.Electron transport phosphorylation (ETP) could be stabilized by adaptive adjustments in the fluidity of the cytoplasmic membrane mediated by changes in fatty acid composition such as those observed. Whether changes in the degree of saturation or in the trans/cisratio are more effective can be decided by studying P. putidaNCTC 10936.