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Updated: Sep 9, 2025
Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Electron transfer mediates position-dependent hydrolytic dichlorination during dichlorophenols biodegradation under
Hanjuan Lv1, Qiang Chi2, Jing Wang3
1Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Abstract:
Polychlorinated phenols (PCPs) are persistent pollutants due to strong C-Cl bonds and toxicity, posing challenges for bioremediation. Although electron acceptor activation can facilitate degradation, the effect of chlorine-substituent positions on isomer-specific biodegradability remains unclear. To address this gap, dichlorophenols (DCPs) were selected as chlorine substitution patterns shape degradation kinetics and microbial responses. Six UASB bioreactors were operated under nitrate-reducing conditions for 130 days to investigate isomer-specific degradation behaviors. The results revealed complete removal (100 %) of ortho-substituted DCPs (2,6-/2,4-DCP) versus limited removal (27.86 ± 2.26 %) of 3,4-DCP (meta-para), establishing a reactivity hierarchy among DCP isomers: dual ortho (2,6) > ortho-para (2,4) > ortho-meta (2,3/2,5) > meta substituted (3,4/3,5). Metagenomic analysis indicated that dehalogenators (Gordonia, Chryseobacterium) were enriched in 2,4-/2,3-DCP systems, nitrate-reducing Pseudomonas dominated the 3,5-DCP system, and Desulfovibrio contributed to electron transfer in the 2,3-DCP system. Molecular docking confirmed that badk (PDB ID: 7P98) and paaF (PDB ID: 6IJK) hydratases regulated degradation kinetics through substrate-specific binding, with computed affinities strongly correlating with observed removal efficiencies. Collectively, these findings demonstrate that chlorine substituent positions fundamentally govern the biodegradability of halogenated aromatics, underscoring the importance of structure-specific bioremediation strategies for effective wastewater treatment.
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