Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are ancient and common in the environment. However, human activities have accelerated their evolution, proliferation and dissemination in and across different ecosystems. ARGs can be transferred between environmental bacteria and human pathogens by horizontal gene transfer (HGT) through mobile genetic elements (MGEs). Recently, both ARB and ARGs have been regarded as emerging pollutants, as they can threaten environmental and human health worldwide. In particular, pollution with multi-resistant ARB and mobile ARGs that are coupled with additional resistance to various pollutants (including antibiotic residues, biocides and heavy metals) on the same MGE has made aquatic ecosystems crucial hotspots for the acquisition and dissemination of both ARB and ARGs in human dominated regions. Freshwater ecosystems, as important sources of drinking water, can provide natural settings for the proliferation and dissemination of bacteria and antibiotic resistance genes (ARGs). The “One Health” concept further emphasizes the importance of monitoring the large-scale dissemination of ARGs. However, knowledge about the geographical patterns and driving mechanisms of bacterial communities and ARGs in natural freshwater environments is limited at large-scale.

The research group (Aquatic EcoHealth Group, Institute of Urban Environment, Chinese Academy of Sciences) led by Prof. Jun Yang investigated the biogeographical patterns of bacterial communities and their ARG profiles in 24 reservoirs across southeast China along a distance gradient of 1800 km. They found that the composition of both bacterial communities and ARG profiles exhibited a significant distance-decay pattern. However, ARG profiles displayed larger differences among different waterbodies than bacterial communities, and the relationship between bacterial communities and ARG profiles was weak. The biogeographical patterns of bacterial communities were simultaneously driven by stochastic and deterministic processes, while ARG profiles were not explained by stochastic processes, indicating a decoupling of bacterial community composition and ARG profiles in inland waters under relatively low-human-impact at large-scale. Overall, this study uncovered the distinct biogeographical patterns of bacterial communities and ARG profiles in inland waters of southeast China under low-anthropogenic impact at a large scale. This study improved our understanding of ARG distribution in inland waters with emphasis on drinking water supply reservoirs, therefore providing the much-needed baseline information for future monitoring and risk assessment of ARGs in drinking water resources.

The research entitled “Biogeographical Patterns of Bacterial Communities and Their Antibiotic Resistomes in the Inland Waters of Southeast China” was published in an international journal “Microbiology Spectrum”. This work was funded by the National Natural Science Foundation of China, the Science & Technology Basic Resources Investigation Program of China, and the Chinese Academy of Sciences.

Bacterial communities and their antibiotic resistomes in reservoirs of southeast China