Bacterial cell membrane adaptation responses on stress caused with the environmental pollutants

The effect of polychlorinated biphenyls on biomass production, lipid accumulation, and on the fatty acid profile of the major membrane lipids of Alcaligenes xylosoxidans isolated from a soil long-term contaminated with polychlorinated biphenyls was examined. The lowest bacterial growth was observed in the presence of biphenyl and polychlorinated biphenyls. On the other hand, the highest growth stimulation was observed in the presence polychlorinated biphenyls. Higher growth ability was observed when polychlorinated biphenyls or 3-chlorobenzoic acid were added after three days of cultivation. Higher lipid accumulation corresponded with lower growth ability. The importance of time when bacterial strain meets polychlorinated biphenyls or 3-chlorobenzoic acid should be emphasized. The addition of toxic organic compound later in stationary growth phase led to better survival and evoked lower membrane adaptation. However, polychlorinated biphenyls or 3-chlorobenzoic acid amendment at the beginning of cultivation stimulated adaptation responses as membrane saturation, cis to trans isomerisation, and branched fatty acids alteration and decreased growth ability. Palmitic acid and 17-cyclopropyl fatty acid were observed as prevalent in the bacterial membrane as well as in the total lipids.