Metagenomics reveals rare and abundant resistome had different resistance and transmission risk in park environment

Urban parks are essential to human life and provide a potential pathway for the spread of antibiotic resistance genes (ARGs) from the environment to humans. However, there are few studies to investigate the risk of ARGs in urban parks, particularly ARGs with different distributions. In this study, we used metagenomics, 16S rRNA gene sequencing and physiochemical properties testing to investigate the profiles of abundant and rare ARGs with different distributions from soil and water in nine urban parks, and then assessed their risk and colonization in the human gut by comparing them with the intestinal resistome of local residents. The results showed that abundant ARGs had higher potential transmission risk, but rare ARGs posed stronger resistance risk, host pathogenic risk and were more likely to colonize the human gut. Notably, rare ARGs contained more high-risk ARGs that may colonize humans. Network analysis showed rare ARGs in water maintain stability of ARGs co-occurrence network. Abundant ARGs were mainly dominated by nutritional factors (e.g., TS), whereas rare ARGs were mainly driven by bacterial community diversity. This study revealed that ARGs in urban parks pose different ecological risk to humans and provided a theoretical basis for public health and environmental management in urban parks. • Abundant ARGs had higher relative abundance and potential transmission risk. • Rare ARGs had higher diversity, host pathogenicity and resistance risk. • Rare ARGs in urban parks contained more high-risk ARGs that may colonize humans. • Abundant and rare ARGs showed different key roles in ARG co-occurrence networks. • TS and bacterial community diversity were main drivers of abundant and rare ARGs.