Owing to the long residence times of water, water reservoirs readily contribute to the accumulation of antibiotic resistant gene (ARG). It is of great public health significance to explore bacterial communities, antibiotic resistomes, and the potential public health risks of water reservoirs. In this study, metagenomic sequencing was used to analyze and compare the bacterial communities, ARG profiles, ARG-horizontal transfer, and ARG-carrying pathogens in the water and sediments of the Dongping Lake Reservoir in the dry and the wet seasons. Compared with that of the sediments, the results showed that both the bacterial communities and ARG profiles in the water were significantly influenced by the seasons, and the total ARG abundance in the dry season was significantly higher than that in the wet season. The total ARG abundance in the sediments was higher than that in water, but the horizontal transfer potential of ARG in the water was higher than that in the sediment. A total of 377 ARG subtypes belonging to 20 ARG types were found in this study. Bacitracin and vancomycin resistance genes were the main ARG types in the water and sediments, respectively, and Proteobacteria and Actinobacteria were the major ARG-carrying bacteria in the water and sediments, respectively. In addition, 30 clinical pathogens carrying ARGs were identified, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica, and Acinetobacter bohemicus. More importantly, two Escherichia coli concurrently carried virulence factor and ARG. In summary, this study revealed that a variety of ARG types existed in the Dongping Lake Reservoir, which has posed potential public health risks by contributing to the horizontal transfer of ARG and the accumulation of clinical pathogens. Therefore, it is necessary to regularly monitor the bacterial community and ARG profile in various water bodies.
Keywords: Dongping Lake Reservoir; antibiotic resistant gene; bacterial community; horizontal transfer; metagenomic sequencing; pathogen.