Distinguishing Effects of Ultraviolet Exposure and Chlorination on the Horizontal Transfer of Antibiotic Resistance Genes in Municipal Wastewater

• Published in: Environmental science & technology Vol. 49; no. 9; pp. 5771 - 5778
• Main Authors: Guo, Mei-Ting, Yuan, Qing-Bin, Yang, Jian
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.05.2015
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics; Chlorine; Conjugation, Genetic; Disinfection; Dose-Response Relationship, Radiation; Drug resistance; Drug Resistance, Microbial - genetics; Drug Resistance, Microbial - radiation effects; E coli; Effects; Escherichia coli - genetics; Escherichia coli - radiation effects; Escherichia coli - ultrastructure; Gene Transfer, Horizontal - radiation effects; Genes, Bacterial; Halogenation - radiation effects; L-Lactate Dehydrogenase - metabolism; Microbial Viability - radiation effects; Permeability; Ultraviolet radiation; Ultraviolet Rays; Waste Water - microbiology; Water treatment plants
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.5b00644

Growing attention has been paid to the dissemination of antibiotic resistance genes (ARGs) in wastewater microbial communities; however, the disinfection processes, as microbial control technologies, have not been evaluated for their impacts on ARGs transfer. In this study, the effects of ultraviolet (UV) disinfection and chlorination on the frequency of ARGs transfer have been explored based on the conjugative transfer model between Gram-negative strains of E. coli. The results indicated that UV disinfection and chlorination exhibit distinct influences on the conjugative transfer. Low UV doses (up to 8 mJ/cm2) had little influence on the frequency of conjugative transfer, and UV exposure only decreased the bacterial number but did not change the cell permeability. By comparison, low chlorine doses (up to 40 mg Cl min/L) significantly promoted the frequency of conjugative transfer by 2–5-fold. The generated chloramine stimulated the bacteria and improved the cell permeability. More pilus were induced on the surface of conjugative cells, which acted as pathways for ARGs transfer. The frequency of ARG transfers was greatly suppressed by high doses of UV (>10 mJ/cm2) or chlorine (>80 mg Cl min/L).