Synchronous response in methanogenesis and anaerobic degradation of pentachlorophenol in flooded soil

•Methanogenesis and anaerobic degradation of PCP were significantly inhibited by 10 mM BES.•CoM more than 10 mM could promote methane formation and speed up the PCP degradation simultaneously.•Methanogenesis and methanogens had an indispensable importance in anaerobic degradation of PCP.•The co-metabolic dechlorination would be more important, relative to the direct dechorination, in anaerobic degradation of PCP in flooded soil. Methanogenesis is commonly mass-produced under anaerobic conditions and serves as a major terminal electron accepting process driving the degradation of organic biomass. In this study, a cofactor of methanogenesis (coenzyme M, CoM) and a classic methanogensis inhibitor (2-bromoethanesulfonate, BES) were added at different concentrations to investigate how methanogenesis would affect PCP degradation in flooded soil. Strikingly, the processes of methanogenesis and PCP degradation were simultaneously promoted with CoM, or inhibited with BES, significantly (p