The Mechanism Insight into Bacterial Degradation of Pentachlorobiphenyl

Bacterial degradation mechanism for high chlorinated pentachlorobiphenyl (PentaCB) with worse biodegradability has not been fully elucidated, which could limit the full remediation of PCBs-combined pollution. In this research, using enzymatic screening method, a new PentaCB-degrading bacterium M. paraoxydans that has not been reported was obtained. The characteristic of its intracellular enzymes, proteome and metabolome variation during PentaCB degradation were investigated systematically. The results showed that PentaCB (PCB101, 1 mg/L) degradation rate could arrive 23.9% within 4 h till complete degradation within 12 h. The intracellular enzyme compound was optimally active at pH 6.0. The 12 up-regulated characterized proteins involved ABC transporter substrate-binding protein, translocase protein TatA and signal peptidase I (SPase I) indicated that functional proteins for PentaCB degradation were present both in the cytoplasm and outer surface of cytoplasmic membrane. There were also 5 differential metabolites strongly associated with above proteins in which the up-regulated 1, 2, 4-benzenetriol was enriched into the degradation pathways of benzoate, chlorocyclohexane, chlorobenzene and aminobenzoate. Bacterial degradation of PentaCB necessitates transmembrane transport, energy consumption, protein export, biofilm formation and quorum sensing. These findings hold significant theory and application value for PCBs biodegradation.