title: Effect of the selective pressure of sub-lethal level of heavy metals on the fate and distribution of ARGs in the catchment scale.
abstract: Our previous study demonstrated that high levels of antibiotic resistance genes (ARGs) in the Haihe River were directly attributed to the excessive use of antibiotics in animal agriculture. The antibiotic residues of the Xiangjiang River determined in this study were much lower than those of the Haihe River, but the relative abundance of 16 detected ARGs (sul1, sul2 and sul3, qepA, qnrA, qnrB, qnrD and qnrS, tetA, tetB, tetW, tetM, tetQ and tetO, ermB and ermC), were as high as the Haihe River particularly in the downstream of the Xiangjiang River which is close to the extensive metal mining. The ARGs discharged from the pharmaceutical wastewater treatment plant (PWWTP) are a major source of ARGs in the upstream of the Xiangjiang River. In the downstream, selective stress of heavy metals rather than source release had a significant influence on the distinct distribution pattern of ARGs. Some heavy metals showed a positive correlation with certain ARG subtypes. Additionally, there is a positive correlation between individual ARG subtypes and heavy metal resistance genes, suggesting that heavy metals may co select the ARGs on the same plasmid of antibiotic resistant bacteria. The co-selection mechanism between specific metal and antibiotic resistance was further confirmed by these isolations encoding the resistance genotypes to antibiotics and metals. To our knowledge, this is the first study on the fate and distribution of ARGs under the selective pressure exerted by heavy metals in the catchment scale. These results are beneficial to understand the fate, and to discern the contributors of ARGs from either the source release or the selective pressure by sub-lethal levels of environmental stressors during their transport on a river catchment scale.
authors.affiliation: College of Environmental Sciences and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China; School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.affiliation: School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China. Electronic address: mao@tju.edu.cn.
authors.forename: Daqing
authors.initials: D
authors.lastname: Mao
authors.affiliation: College of Environmental Sciences and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China. Electronic address: luoy@nankai.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D002681:China; D004352:Drug Resistance, Microbial / Q000187:drug effects* / Q000235:genetics*; D004784:Environmental Monitoring; D005798:Genes, Bacterial / Q000187:drug effects*; D019216:Metals, Heavy / Q000032:analysis / Q000633:toxicity*; D045483:Rivers / Q000737:chemistry / Q000382:microbiology; D062065:Wastewater / Q000032:analysis / Q000633:toxicity*
chemical_list: D000900:Anti-Bacterial Agents; D019216:Metals, Heavy; D062065:Wastewater
keywords: Antibiotic resistance genes; Co-resistance; Heavy metals; River catchment scale; Xiangjiang river