Marine Dehalogenator and Its Chaperones: Microbial Duties and Responses in 2,4,6-Trichlorophenol Dechlorination

Marine environments contain diverse halogenated organiccompounds(HOCs), both anthropogenic and natural, nourishing a group of versatileorganohalide-respiring bacteria (OHRB). Here, we identified a novelOHRB (Peptococcaceae DCH) with conserved motifs but phylogeneticallydiverse reductive dehalogenase catalytic subunit (RdhAs) from marineenrichment culture. Further analyses clearly demonstrate the horizontalgene transfer of rdhAs among marine OHRB. Moreover,2,4,6-trichlorophenol (TCP) was dechlorinated to 2,4-dichlorophenoland terminated at 4-chlorophenol in culture. Dendrosporobacter and Methanosarcina were the two dominantgenera, and the constructed and verified metabolic pathways clearlydemonstrated that the former provided various substrates for othermicrobes, while the latter drew nutrients, but might provide littlebenefit to microbial dehalogenation. Furthermore, Dendrosporobacter could readily adapt to TCP, and sporulation-related proteins of Dendrosporobacter were significantly upregulatedin TCP-free controls, whereas other microbes (e.g., Methanosarcina and Aminivibrio) became more active, providing insightsinto how HOCs shape microbial communities. Additionally, sulfate couldaffect the dechlorination of Peptococcaceae DCH, but not debromination.Considering their electron accessibility and energy generation, theresults clearly demonstrate that bromophenols are more suitable thanchlorophenols for the enrichment of OHRB in marine environments. Thisstudy will greatly enhance our understanding of marine OHRB (rdhAs), auxiliary microbes, and microbial HOC adaptive mechanisms. Advancing the understanding of synergisticinteractionsin marine OHRB and their adaptive mechanisms to HOCs.