As a new type of environmental pollutant,antibiotic resistance genes(ARGs)pose a huge challenge to global health.Horizontal gene transfer(HGT)represents an important route for the spread of ARGs.The widespread use of ...As a new type of environmental pollutant,antibiotic resistance genes(ARGs)pose a huge challenge to global health.Horizontal gene transfer(HGT)represents an important route for the spread of ARGs.The widespread use of sulfamethazine(SM2)as a broad-spectrum bacteriostatic agent leads to high residual levels in the environment,thereby increasing the spread of ARGs.Therefore,we chose to study the effect of SM2 on the HGT of ARGs mediated by plasmid RP4 from Escherichia coli(E.coli)HB101 to E.coli NK5449 as well as its mechanism of action.The results showed that compared with the control group,SM2 at concentrations of 10 mg/L and 200 mg/L promoted the HGT of ARGs,but transfer frequency decreased at concentrations of 100 mg/L and 500 mg/L.The transfer frequency at 200 mg/L was 3.04×10^(−5),which was 1.34-fold of the control group.The mechanism of SM2 improving conjugation transfer is via enhancement of the mRNA expression of conjugation genes(trbBP,trfAP)and oxidative stress genes,inhibition of the mRNA expression of vertical transfer genes,up regulation of the outer membrane protein genes(ompC,ompA),promotion of the formation of cell pores,and improvement of the permeability of cell membrane to promote the conjugation transfer of plasmid RP4.The results of this study provide theoretical support for studying the spread of ARGs in the environment.展开更多
Chlorpyrifos is a pesticide widely used in agricultural production with a relatively long residual half-life in soil.Addressing the problem of residual chlorpyrifos is of universal concern.In this study,rice hull bioc...Chlorpyrifos is a pesticide widely used in agricultural production with a relatively long residual half-life in soil.Addressing the problem of residual chlorpyrifos is of universal concern.In this study,rice hull biochar was used as an immobilized carrier to prepare the immobilized strain H27 for the remediation of chlorpyrifos-contamination soil.Soil microorganisms after remediation were investigated by ecotoxicological methods.The immobilized strain H27 had the highest removal rate of chlorpyrifos when 10%bacterial solution was added to the liquid medium containing 0.075-0.109 mm diameter biochar cultured for 22 hr.This study on the removal of chlorpyrifos by immobilized strain H27 showed that the initial concentration of chlorpyrifos in solution was 25mg/L,and the removal rate reached 97.4%after 7 days of culture.In the soil,the removal rate of the immobilized bacteria group increased throughout the experiment,which was significantly higher than that of the free bacteria and biochar treatment groups.The Biolog-ECO test,T-RFLP and RT-RCR were used to study the effects of the soil microbial community and nitrogen cycling functional genes during chlorpyrifos degradation.It was found that ICP group had the highest diversity index among the four treatment groups.The microflora of segment containing 114 bp was the dominant bacterial community,and the dominant microflora of the immobilized bacteria group was more evenly distributed.The influence of each treatment group on ammonia-oxidizing bacteria(AOB)was greater than on ammonia-oxidizing archaea(AOA).This study offers a sound scientific basis for the practical application of immobilized bacteria to reduce residual soil pesticides.展开更多
基金supported by the National Natural Science Foundation of China(No.41671320)the Natural Science Foundation of Shandong Province,China(No.ZR2016JL029)and the Special Funds of Taishan Scholar of Shandong Province,China.
文摘As a new type of environmental pollutant,antibiotic resistance genes(ARGs)pose a huge challenge to global health.Horizontal gene transfer(HGT)represents an important route for the spread of ARGs.The widespread use of sulfamethazine(SM2)as a broad-spectrum bacteriostatic agent leads to high residual levels in the environment,thereby increasing the spread of ARGs.Therefore,we chose to study the effect of SM2 on the HGT of ARGs mediated by plasmid RP4 from Escherichia coli(E.coli)HB101 to E.coli NK5449 as well as its mechanism of action.The results showed that compared with the control group,SM2 at concentrations of 10 mg/L and 200 mg/L promoted the HGT of ARGs,but transfer frequency decreased at concentrations of 100 mg/L and 500 mg/L.The transfer frequency at 200 mg/L was 3.04×10^(−5),which was 1.34-fold of the control group.The mechanism of SM2 improving conjugation transfer is via enhancement of the mRNA expression of conjugation genes(trbBP,trfAP)and oxidative stress genes,inhibition of the mRNA expression of vertical transfer genes,up regulation of the outer membrane protein genes(ompC,ompA),promotion of the formation of cell pores,and improvement of the permeability of cell membrane to promote the conjugation transfer of plasmid RP4.The results of this study provide theoretical support for studying the spread of ARGs in the environment.
基金This work was supported by the National Natural Science Foundation of China(Nos.42277039 and 42207026)the Natural Science Foundation of Shandong Province,China(No.ZR2022QD098)the Special Funds of Taishan Scholar of Shandong Province,China.
文摘Chlorpyrifos is a pesticide widely used in agricultural production with a relatively long residual half-life in soil.Addressing the problem of residual chlorpyrifos is of universal concern.In this study,rice hull biochar was used as an immobilized carrier to prepare the immobilized strain H27 for the remediation of chlorpyrifos-contamination soil.Soil microorganisms after remediation were investigated by ecotoxicological methods.The immobilized strain H27 had the highest removal rate of chlorpyrifos when 10%bacterial solution was added to the liquid medium containing 0.075-0.109 mm diameter biochar cultured for 22 hr.This study on the removal of chlorpyrifos by immobilized strain H27 showed that the initial concentration of chlorpyrifos in solution was 25mg/L,and the removal rate reached 97.4%after 7 days of culture.In the soil,the removal rate of the immobilized bacteria group increased throughout the experiment,which was significantly higher than that of the free bacteria and biochar treatment groups.The Biolog-ECO test,T-RFLP and RT-RCR were used to study the effects of the soil microbial community and nitrogen cycling functional genes during chlorpyrifos degradation.It was found that ICP group had the highest diversity index among the four treatment groups.The microflora of segment containing 114 bp was the dominant bacterial community,and the dominant microflora of the immobilized bacteria group was more evenly distributed.The influence of each treatment group on ammonia-oxidizing bacteria(AOB)was greater than on ammonia-oxidizing archaea(AOA).This study offers a sound scientific basis for the practical application of immobilized bacteria to reduce residual soil pesticides.
