Antibiotic resistome in a large urban-lake drinking water source in middle China: Dissemination mechanisms and risk assessment

The increasing pollution of urban drinking water sources by antibiotic resistance genes (ARGs) threatens human health worldwide. However, the distribution and influencing factors of ARGs, especially how to reveal the risks of ARGs in this environment remains unclear. Hence, Chaohu Lake was selected as an example to investigate the characteristics of ARGs and explore the interactions among physicochemical factors, microorganisms, and ARGs by metagenomic approach. In this work, 75 ARG subtypes with an average of 30.4 × /Gb (ranging from 15.2 ×/Gb to 57.9 ×/Gb) were identified, and multidrug and bacA were most frequent in Chaohu Lake. Non-random co-occurrence patterns and potential host bacteria of ARGs were revealed through co-occurrence networks. Microbial community and mobile genetic elements (MGEs) were the major direct factors in ARG profiles. The dissemination of ARGs was mainly driven by plasmids. Considering the interactions among MGEs, human bacterial pathogens, and ARGs, antibiotic resistome risk index (ARRI) was proposed to manifest the risks of ARGs. Overall, our work systemically investigated the composition and associated factors of ARGs and built ARRI to estimate the potential risks of ARGs in a typical urban drinking water source, providing an intuitive indicator for managing similar lakes.