Using bioelectrochemical systems(BESs)to provide electrochemically generated hydrogen is a promising technology to provide electron donors for reductive dechlorination by organohalide-respiring bacteria.In this study,...Using bioelectrochemical systems(BESs)to provide electrochemically generated hydrogen is a promising technology to provide electron donors for reductive dechlorination by organohalide-respiring bacteria.In this study,we inoculated two syntrophic dechlorinating cultures containing Dehalobacter and Dehalobacterium to sequentially transform chloroform(CF)to acetate in a BES using a graphite fiber brush as the electrode.In this co-culture,Dehalobacter transformed CF to stoichiometric amounts of dichloromethane(DCM)via organohalide respiration,whereas the Dehalobacterium-containing culture converted DCM to acetate via fermentation.BES were initially inoculated with Dehalobacter,and sequential cathodic potentials of-0.6,-0.7,and -0.8 V were poised after consuming three CF doses(500 μM)per each potential during a time-span of 83 days.At the end of this period,the accumulated DCM was degraded in the following seven days after the inoculation of Dehalobacterium.At this point,four consecutive amendments of CF at increasing concentrations of 200,400,600,and 800 μM were sequentially transformed by the combined degradation activity of Dehalobacter and Dehalobacterium.The Dehalobacter 16S rRNA gene copies increased four orders of magnitude during the whole period.The coulombic efficiencies associated with the degradation of CF reached values>60% at a cathodic potential of -0.8 V when the degradation rate of CF achieved the highest values.This study shows the advantages of combining syntrophic bacteria to fully detoxify chlorinated compounds in BESs and further expands the use of this technology for treating water bodies impacted with pollutants.展开更多
Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world.Chlorophenoxy herbicides are toxic,chemically stable,and can migrate into groundwater through soil leaching,pos...Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world.Chlorophenoxy herbicides are toxic,chemically stable,and can migrate into groundwater through soil leaching,posing a significant threat to drinking water safety and human health.Chlorophenoxy herbicides in groundwater aquifers are subject to anaerobic processes;however,the pathway and microbiology involved in the attenuation of chlorophenoxy herbicides under anaerobic condition are largely unknown.Here,the anaerobic degradation process of 2,4,5-trichlorophenoxyacetic acid(2,4,5-T),a typical chlorophenoxy herbicide,was investigated.Results The initial 52.5±2.3μM 2,4,5-T was completely degraded by a sediment-derived microbial consortium,with 3,4-dichlorophenol,2,5-dichlorophenol,3-chlorophenol(3-CP)and phenol being identified as the intermediate products.Reductive dechlorination of 3-CP to phenol and the subsequent elimination of phenol were the key transformation steps in the overall degradation process of 2,4,5-T.Amplicon sequencing suggested that Dehalobacter,Sulfuricurvum,Bacteroides,Acetobacterium,and Clostridium sensu stricto 7 might contribute to the transformation of 2,4,5-T to phenol,and Smithella,Syntrophorhabdus,Methanofollis and Methanosaeta likely cooperated to accomplish the complete mineralization of phenol.Conclusions This study reported the anaerobic degradation of 2,4,5-T via reductive dechlorination and the subsequent syntrophic metabolization of phenol,an intermediate product transformed from 2,4,5-T.Dehalobacter was identified as the organohalide-respiring population catalyzing the reductive dechlorination reaction.Syntrophorhabdus and methanogenic populations were likely involved in anaerobic phenol oxidation and facilitated the complete mineralization of 2,4,5-T.展开更多
基金supported by the Spanish Ministry of Science,Innovation and Universities projects CTM2017-91879-EXP and PID2019-103989RB-100a predoctoral grant from UAB(PIF 2017e2018).
文摘Using bioelectrochemical systems(BESs)to provide electrochemically generated hydrogen is a promising technology to provide electron donors for reductive dechlorination by organohalide-respiring bacteria.In this study,we inoculated two syntrophic dechlorinating cultures containing Dehalobacter and Dehalobacterium to sequentially transform chloroform(CF)to acetate in a BES using a graphite fiber brush as the electrode.In this co-culture,Dehalobacter transformed CF to stoichiometric amounts of dichloromethane(DCM)via organohalide respiration,whereas the Dehalobacterium-containing culture converted DCM to acetate via fermentation.BES were initially inoculated with Dehalobacter,and sequential cathodic potentials of-0.6,-0.7,and -0.8 V were poised after consuming three CF doses(500 μM)per each potential during a time-span of 83 days.At the end of this period,the accumulated DCM was degraded in the following seven days after the inoculation of Dehalobacterium.At this point,four consecutive amendments of CF at increasing concentrations of 200,400,600,and 800 μM were sequentially transformed by the combined degradation activity of Dehalobacter and Dehalobacterium.The Dehalobacter 16S rRNA gene copies increased four orders of magnitude during the whole period.The coulombic efficiencies associated with the degradation of CF reached values>60% at a cathodic potential of -0.8 V when the degradation rate of CF achieved the highest values.This study shows the advantages of combining syntrophic bacteria to fully detoxify chlorinated compounds in BESs and further expands the use of this technology for treating water bodies impacted with pollutants.
基金supported by the Natural Science Foundation of China(42377133,42177220)with additional support from the Natural Science Foundation(Joint Fund)of Liaoning Province(2023JH2/101700354,2023JH2/101800044).
文摘Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world.Chlorophenoxy herbicides are toxic,chemically stable,and can migrate into groundwater through soil leaching,posing a significant threat to drinking water safety and human health.Chlorophenoxy herbicides in groundwater aquifers are subject to anaerobic processes;however,the pathway and microbiology involved in the attenuation of chlorophenoxy herbicides under anaerobic condition are largely unknown.Here,the anaerobic degradation process of 2,4,5-trichlorophenoxyacetic acid(2,4,5-T),a typical chlorophenoxy herbicide,was investigated.Results The initial 52.5±2.3μM 2,4,5-T was completely degraded by a sediment-derived microbial consortium,with 3,4-dichlorophenol,2,5-dichlorophenol,3-chlorophenol(3-CP)and phenol being identified as the intermediate products.Reductive dechlorination of 3-CP to phenol and the subsequent elimination of phenol were the key transformation steps in the overall degradation process of 2,4,5-T.Amplicon sequencing suggested that Dehalobacter,Sulfuricurvum,Bacteroides,Acetobacterium,and Clostridium sensu stricto 7 might contribute to the transformation of 2,4,5-T to phenol,and Smithella,Syntrophorhabdus,Methanofollis and Methanosaeta likely cooperated to accomplish the complete mineralization of phenol.Conclusions This study reported the anaerobic degradation of 2,4,5-T via reductive dechlorination and the subsequent syntrophic metabolization of phenol,an intermediate product transformed from 2,4,5-T.Dehalobacter was identified as the organohalide-respiring population catalyzing the reductive dechlorination reaction.Syntrophorhabdus and methanogenic populations were likely involved in anaerobic phenol oxidation and facilitated the complete mineralization of 2,4,5-T.
