The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution syst...The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution system under simulated conditionswere explored.The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH_(2)Cl was higher than in the control groups.Therewas no similar phenomenon in biofilm.In thewater of reactors containing NaClO,the aphA and bla geneswere lower than in the antibiotic resistant bacteria group,while both genes were higher in the water of reactors with NH_(2)Cl than in the control group.Chloramine may promote the transfer of ARGs in the water phase.Both genes in the biofilm of the reactors containing chlorine were lower than the control group.Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm(p<0.05).The results of the sequencing assay showed that bacteria in the biofilm,in the presence of disinfectant,were primarily Gram-negative.1.0 mg/L chlorine decreased the diversity of the community in the biofilm.The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.展开更多
Advanced oxidation processes (AOPs) exhibit significant potential forwater disinfection dueto their generation of large quantities of highly oxidizing free radicals. However, the neglectof viable but nonculturable (VB...Advanced oxidation processes (AOPs) exhibit significant potential forwater disinfection dueto their generation of large quantities of highly oxidizing free radicals. However, the neglectof viable but nonculturable (VBNC) cells obscures their true disinfection efficacy and potentialenvironmental health risks. Therefore, the study evaluated the disinfection effectivenessand mechanisms of typical AOPs, including Fe/H_(2)O_(2), Fe/persulfate (PS), and O_(3), fromthe perspective of the production of VBNC bacteria. The results indicate that Fe/PS exhibitsthe strongest bacterial inactivation rate (99.94%), and the cells lose their ability to reactivate.Fe/H_(2)O_(2) and O_(3) induce more cells to enter the VBNC state compared to Fe/PS. Moreover,different AOPs result in varying levels of free radical production and utilization efficiency,with SO(4)^(·−) and O_(3) exhibiting greater selectivity in deactivating bacteria comparedto HO^(·). The inhibition of VBNC bacteria production by Fe/PS treatment may be attributed tothe combined action of HO^(·) and SO(4)^(·−) on microorganisms, leading to oxidative stress andmetabolic disruption in bacteria through the inhibition of biofilm formation and aminoacyltRNAbiosynthesis (p < 0.05), thereby causing direct bacterial death rather than entry intothe VBNC state. In contrast, Fe/H_(2)O_(2) and O_(3) result in the upregulation of the metabolismof alanine, aspartate, and glutamate, as well as styrene degradation capacity by the bacteria,leading to the production of more VBNC bacteria. Overall, the study offers insights intomitigating potential biological risks in water disinfection and developing environmentallyfriendly and efficient disinfection technologies.展开更多
基金supported by the Natural Science Foundation of China(No.52070145,51778453).
文摘The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution system under simulated conditionswere explored.The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH_(2)Cl was higher than in the control groups.Therewas no similar phenomenon in biofilm.In thewater of reactors containing NaClO,the aphA and bla geneswere lower than in the antibiotic resistant bacteria group,while both genes were higher in the water of reactors with NH_(2)Cl than in the control group.Chloramine may promote the transfer of ARGs in the water phase.Both genes in the biofilm of the reactors containing chlorine were lower than the control group.Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm(p<0.05).The results of the sequencing assay showed that bacteria in the biofilm,in the presence of disinfectant,were primarily Gram-negative.1.0 mg/L chlorine decreased the diversity of the community in the biofilm.The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.
基金supported by Shandong Provincial Natural Science Foundation,China(Nos.ZR2020ZD34 and ZR2023YQ031)the National Natural Science Foundation of China(Nos.42077391 and 42377428)the Instrument Improvement Funds of ShandongUniversity Public Technology Platform(No.ts20230108).
文摘Advanced oxidation processes (AOPs) exhibit significant potential forwater disinfection dueto their generation of large quantities of highly oxidizing free radicals. However, the neglectof viable but nonculturable (VBNC) cells obscures their true disinfection efficacy and potentialenvironmental health risks. Therefore, the study evaluated the disinfection effectivenessand mechanisms of typical AOPs, including Fe/H_(2)O_(2), Fe/persulfate (PS), and O_(3), fromthe perspective of the production of VBNC bacteria. The results indicate that Fe/PS exhibitsthe strongest bacterial inactivation rate (99.94%), and the cells lose their ability to reactivate.Fe/H_(2)O_(2) and O_(3) induce more cells to enter the VBNC state compared to Fe/PS. Moreover,different AOPs result in varying levels of free radical production and utilization efficiency,with SO(4)^(·−) and O_(3) exhibiting greater selectivity in deactivating bacteria comparedto HO^(·). The inhibition of VBNC bacteria production by Fe/PS treatment may be attributed tothe combined action of HO^(·) and SO(4)^(·−) on microorganisms, leading to oxidative stress andmetabolic disruption in bacteria through the inhibition of biofilm formation and aminoacyltRNAbiosynthesis (p < 0.05), thereby causing direct bacterial death rather than entry intothe VBNC state. In contrast, Fe/H_(2)O_(2) and O_(3) result in the upregulation of the metabolismof alanine, aspartate, and glutamate, as well as styrene degradation capacity by the bacteria,leading to the production of more VBNC bacteria. Overall, the study offers insights intomitigating potential biological risks in water disinfection and developing environmentallyfriendly and efficient disinfection technologies.
