Occurrence and distribution of antibiotic resistance genes in lakes and reservoirs from water-receiving area of Eastern Route of the South-to-North Water Diversion Project, Northern China

To characterize antibiotic resistance genes (ARGs) in surface waterbodies in Shandong Province, and to understand the occurrence, diversity and resistance mechanism of ARGs, nine aquatic ecosystems were selected and evaluated regarding occurrence of ARGs in the period from 2018 to 2019. Thirty-three types and 242 subtypes of ARGs were detected in the nine waterbodies with the most subtypes in Wohushan (242) and Jihongtan (235), and the fewest ARGs in Datun (213) and Mishan (221). Among the top nine ARG types, MacB, BcrA, CarA and TetW were the dominant ARGs in these samples. Four groups of the study sites were distinguished by cluster analysis, indicating different distribution characteristics of ARGs in these waterbodies, and regional differences in ARG contamination. Efflux pumps were the predominant resistance mechanism in all the waterbodies in terms of both subtype number (49.2%) and abundance (70.4%), followed by operon, antibiotic inactivation and others. Our findings provide comprehensive information to better understand the contamination level of ARGs on a local level as well as for global considerations, and may be practically helpful for the prevention and control of ARG pollution.