engleski

Insights into flexibility of Rhodococci in transformation of PCBs

Perhaps one of the most known POPs, polychlorinated biphenyls (PCBs), comprise a family of about 200 related compounds. Even though the manufacture and sale of PCBs were banned decades ago, they are continuously entering environment, mainly via point source pollution due to inadequately managed hazardous waste sites, by leaching from electrical equipment or during treatment of contaminated wastes. Microbial biodegradation of PCBs has been a subject of intensive research but until now, most of our knowledge on PCBs metabolism come from studies carried out on Burkholderia xenovorans LB400 and Rhodococcus sp. RHA1, two PCBs degraders whose genomes have been fully sequenced. Our knowledge on enzymes involved in PCB metabolism remains fragmentary and diversity of bacterial metabolisms in transforming PCBs is highly underestimated. In order to explore the metabolic pleiotropy of the Rhodococci we settled an experiment aiming at monitoring the transformation of structurally different PCB congeners (2, 4, 4'-trichlorobiphenyl, 2, 2', 5, 5'-tetrachlorobiphenyl and 2, 4, 3'-trichlorobiphenyl) in four Rhodococci isolated from PCB-contaminated environments. These strains showed strong ability to transform various PCBs. Transformation products were detected by gas-chromatography and identified by -mass spectrometry on aliquots of microbial cultures. We propose that bacteria belonging to the genus Rhodococcus do not only transform PCBs using the classical bph pathway, but also through a complex interplay of different catabolic pathway modules. Our study suggests that the PCB catabolic potential of Rhodococciis not yet fully understood.

PCBs ; biotransformation ; catabolic pathway ; intermediates ; Rhodococcus ; GC-MS

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