Unraveling metabolic flexibility of rhodococci in PCB transformation

Even though the genetic attributes suggest presence of multiple degradation pathways, most rhodococci are known to transform PCBs only via regular biphenyl (bph) pathway. Using GC-MS analysis, we monitored products formed during transformation 2,4,4′-trichlorobiphenyl (PCB-28), 2,2′,5,5′-tetrachlorobiphenyl (PCB-52) and 2,4,3′-trichlorobiphenyl (PCB-25) by previously characterized PCB-degrading Z6, T6, R2, Z57, with aim explore their metabolic pleiotropy in PCB transformations. A striking number different (TPs) carrying a phenyl ring as substituent, both those generated part bph pathway an array unexpected TPs, implied curious ability. We hypothesized that studied rhodococcal isolates, besides one, use at least two alternative pathways for transformation, including leading acetophenone formation (via 3,4 (4,5) dioxygenase attack on molecule), third sideway includes stepwise oxidative decarboxylation aliphatic side chain 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate. Structure identified chlorinated benzoic acids acetophenones allowed us hypothesize first were outcome ring-hydroxylating ability 2,3 (5,6) positions well dechlorination activity both, -ortho -para positions. propose several TPs produced could have caused triggering In conclusion, this study proposed strategies which allows them circumvent potential negative aspect overall