title: Fate and proliferation of typical antibiotic resistance genes in five full-scale pharmaceutical wastewater treatment plants.
abstract: This study investigated the characteristics of 10 subtypes of antibiotic resistance genes (ARGs) for sulfonamide, tetracycline, β-lactam and macrolide resistance and the class 1 integrase gene (intI1). In total, these genes were monitored in 24 samples across each stage of five full-scale pharmaceutical wastewater treatment plants (PWWTPs) using qualitative and real-time quantitative polymerase chain reactions (PCRs). The levels of typical ARG subtypes in the final effluents ranged from (2.08±0.16)×10(3) to (3.68±0.27)×10(6) copies/mL. The absolute abundance of ARGs in effluents accounted for only 0.6%-59.8% of influents of the five PWWTPs, while the majority of the ARGs were transported to the dewatered sludge with concentrations from (9.38±0.73)×10(7) to (4.30±0.81)×10(10) copies/g dryweight (dw). The total loads of ARGs discharged through dewatered sludge was 7-308 folds higher than that in the raw influents and 16-638 folds higher than that in the final effluents. The proliferation of ARGs mainly occurs in the biological treatment processes, such as conventional activated sludge, cyclic activated sludge system (CASS) and membrane bio-reactor (MBR), implying that significant replication of certain subtypes of ARGs may be attributable to microbial growth. High concentrations of antibiotic residues (ranging from 0.14 to 92.2 mg/L) were detected in the influents of selected wastewater treatment systems and they still remain high residues in the effluents. Partial correlation analysis showed significant correlations between the antibiotic concentrations and the associated relative abundance of ARG subtypes in the effluent. Although correlation does not prove causation, this study demonstrates that in addition to bacterial growth, the high antibiotic residues within the pharmaceutical WWTPs may influence the proliferation and fate of the associated ARG subtypes.
authors.affiliation: College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China.
authors.forename: Jilu
authors.initials: J
authors.lastname: Wang
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 Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China.
authors.forename: Quanhua
authors.initials: Q
authors.lastname: Mu
authors.affiliation: College of Environmental Science 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: D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial; D004364:Pharmaceutical Preparations / Q000032:analysis; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004364:Pharmaceutical Preparations; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Antibiotic resistance gene; Bio-treatment process; Pharmaceutical wastewater treatment plant