Study On The Biodegradation Of Trimethoprim Coupled With Different Electron Accpetors In Anaerobic System

Wastewater treatment plants are an important source of antibiotic resistance genes(ARG)and antibiotic resistance bacteria(ARB).How to improve the antibiotic detoxification/degradation efficiency and effectively block the spread of ARGs is a major scientific and technical issue in the environmental field.Based on the requirement of urgent removal of sulphonamides(SAs)frequently detected in aquatic systems and obligatory control of the antibiotics resistance gene(ARGs),the biodegradation of SAs was innovatively combined with anaerobic respiration in this study.Trimethoprim(TMP)is an antibiotic belonging to SAs frequently detected in various environments.Microorganisms are the main drivers of emerging antibiotic contaminants degradation in the environment.However,the feasibility and stability of anaerobic biodegradation of TMP coupled with different electron acceptors remain poorly understood.The main contents of this study include investigating the biodegradation characteristics,transformation pathway and core microbiome feature of TMP when distributed electron acceptors(sulfate,nitrate and ferric iron)and stationary electron acceptor(the anode in bioelectrochemical system)were used.Several TMP-degrading microbial consortium was successfully enriched with municipal activated sludge/river sediment as the initial inoculum.The acclimated consortium is capable of transforming TMP through demethylation,and then the hydroxyl-substituted demethylated product(4-desmethyl-TMP)was further degraded with sulfate as an electron acceptor.Biodegradation of TMP followed a 3-parameter sigmoid kinetics model.The potential degraders(Acetobacterium,Desulfovibrio,Desulfobulbus,and unidentified Peptococcaceae)and fermenters(Lentimicrobium and Petrimonas)were significantly enriched in the acclimated consortium.The activated sludge and river sediment acclimated TMP-degrading consortium shared similar core microbiome.The removal of TMP with the current production simultaneously by the enriched bioanode communities(with an electrode as an electron acceptor)in the presence or absence of co-matrix sodium acetate was confirmed.The presence of co-matrix sodium acetate is closely related to the enhanced biodegradation of TMP and improved current production in the bioanode.When TMP was used as the sole electron donor,the degradation rate and efficiency of TMP(192h,57% vs 24 h,99%)and current production(0.075 mA vs 0.35 mA)was obviously decreased compared to the co-metabolism model.More importantly,the anaerobic biodegradation of TMP could be also coupled with other electron acceptors such as nitrate and ferric iron.The supply of electron acceptors could obviously enhance the TMP degradation efficiency with different initial inoculums.The results from this study is to lay a theoretical and technical foundation for the enhanced removal of TMP from aquatic systems and to make an evaluation on the TMP fate mediated with environmental microbes in real environments.