Phosphorus-31 nuclear magnetic resonance study of the effect of pentachlorophenol (PCP) on the physiologies of PCP-degrading microorganisms

Free and agarose-encapsulated pentachlorophenol (PCP)-degrading Sphingomona s sp. isolates UG25 and UG30 were compared to Sphingomonas chlorophenolica ATCC 39723 with respect to the ability to degrade PCP. Pretreatment of the UG25 and UG30 strains with 50 mug of PCP per ml enabled the cells to subseq uently degrade higher levels of this environmental pollutant. Similar treat ment of ATCC 39723 cells had no effect on the level of PCP degraded by this strain. Phosphorus-31 nuclear magnetic resonance spectra of agarose-immobi lized strains UG25 and UG30 grown in the absence of PCP showed that there w as marked deenergization of the cells upon exposure to a nonlethal concentr ation of PCP (120 mug/ml). For example, no transmembrane pH gradient was ob served, and the ATP levels were lower than the levels obtained in the absen ce of PCP. The transmembrane pH gradient and ATP levels were restored once the immobilized cells had almost completely degraded the PCP in the perfusi on medium. PCP-pretreated cells, on the other hand, maintained their transm embrane pH gradient and ATP levels even in the presence of high levels of P CP. The ability of PCP-pretreated strain UG25 and UG30 cells to remain ener gized in the presence of PCP was shown to correlate with an altered membran e phospholipid profile; these cells had a higher concentration of cardiolip in than cells cultured in the absence of PCP. Strain ATCC 39723, which did not degrade higher levels of PCP after PCP pretreatment, did not show this response.