Prevalence of class 1 integron and its gene cassettes carrying antibiotic resistance genes in drinking water treatment and distribution systems  

作　　者：Shengnan Liu Zihan Li Yan Shen Shuyu Jia Peng Liu Xu-Xiang Zhang 

机构地区：[1]State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing 210023,China [2]College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China

出　　处：《Frontiers of Environmental Science & Engineering》2024年第10期115-126,共12页环境科学与工程前沿（英文）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.52025102,52192682,and 52200057);the Jiangsu Funding Program for Excellent Postdoctoral Talent(China)(No.2022ZB35).

摘　　要：Class 1 integrons are vital mobile genetic elements involved in the environmental transmission of antibiotic resistance genes(ARGs).However,knowledge about the diversity and abundance of class 1 integrons and gene cassettes during drinking water treatment and distribution is still limited.In this study,we aimed to uncover the prevalence of class 1 integrons in the drinking water treatment and distribution systems with the combination of culture-dependent and culture-independent methods.Further,we applied the nanopore sequencing method to characterize the diversity and arrangement of ARGs carried by class 1 integron-associated gene cassettes.A total of 42 isolates were inti-positive among the 208 strains isolated from drinking water,which tended to confer multi-drug resistance compared with intll-negative isolates.The absolute abundance of the intl1 average i.15×10^(9) copies/L in the source water and underwent the most significant reduction of over 99.9% after liquid chiorine disinfection.Furthermore,nanopore sequencing revealed that the class 1 integron-associated gene cassettes carried 51 subtypes of ARGs in drinking water,mainly conferring resistance to aminoglycosides and trimethoprim.The treatment processes,especially liquid chlorine disinfection,reduced most of the ARGs carried by gene cassettes,though some of the ARG subtypes persisted along the treatment and distribution ike aac(6)-Il,aadA,and dfrB2.The antibiotic resistance gene cassette array laac(6')-Ⅱ arr was most frequently detected,especially in the chlorinated water.This study underlined that drinking water was potential reservoir for integron-mediated ARGs transfer,indicating that the health risks of resistance gene cassettes in class 1 integrons deserved urgent attention.

关 键 词：Class 1 integron Antibiotic resistance genes Drinkingwater Genecassettearrays Liquid chlorine disinfection 

分 类 号：TU991.2[建筑科学—市政工程] R123[医药卫生—环境卫生学]