Abstract
Adaptive mechanism and efflux-transport system of Pseudomonas sp. LE2 were investigated to understand how this microorganism survives in lindane-contaminated environments. Adaptive mechanism was demonstrated by changes in the ratio of total saturated to unsaturated fatty acids in cells grown on glucose with or without lindane. The ratio of total saturated to unsaturated fatty acids in cells grown with lindane was 0.9, which was comparable to 0.5 in cells grown without lindane. Lindane significantly affected in vitro the membrane of cells grown without lindane by decreasing membrane transition temperature from about 25 to 22°C at 8μM. Less fluidizing effect of lindane on the membrane of cells that had grown with lindane was observed, giving about 18% of polarization percentage ratio, which was significantly lower than about 52% in cells grown without lindane. When lindane was incubated with Pseudomonas sp. LE2 cell suspensions, it accumulated in cells by simple diffusion mechanism. A membrane transport inhibitor, sodium azide, increased considerably lindane accumulation in cells, showing significant inhibition of lindane efflux from cells. These results suggest the view that Pseudomonas sp. LE2 capable of growing in the presence of lindane is able to adapt to the fluidizing action of lindane by incorporating saturated fatty acids into membrane lipids and eliminating lindane from cells by an energy-dependent efflux mechanism.
