Alterations in fatty acid composition and fluidity of cell membranes affect the accumulation of PCB congener 2,2′,5,5′‐tetrachlorobiphenyl by Ralstonia eutropha H850

The effect of alterations in fatty acid composition and fluidity of cell membranes on the accumulation of PCB congener 2,2′,5,5′‐tetrachlorobiphenyl (TeCB) by Ralstonia eutropha (formerly Alcaligenes eutrophus ) H850 was studied. Cells of R eutropha H850 grown on either biphenyl or fructose were used. Significant increases in saturated fatty acid composition and decreases in membrane fluidity of bacteria grown on biphenyl at 28 °C were observed compared with those grown on fructose at 17 or 28 °C. The ratio of saturated fatty acids to unsaturated fatty acids and membrane fluidity of R eutropha H850 grown on biphenyl at 28 °C resembled those of cells grown on fructose at 37 °C. No inhibition effect of the uncoupler 2,4‐dinitrophenol (2,4‐DNP) on TeCB accumulation was observed, suggesting an energy‐independent mechanism for TeCB accumulation in cells of R eutropha H850. The amount of TeCB accumulated was considerably higher in R eutropha H850 grown on fructose at 17 and 28 °C than when grown on biphenyl at 28 °C. Similar amounts of TeCB accumulated in bacteria grown on biphenyl at 28 °C as compared with those grown on fructose at 37 °C. These results suggest the alterations in fatty acid composition and membrane fluidity of R eutropha H850 may affect the accumulation of TeCB. © 2002 Society of Chemical Industry