Microbial communities, resistance genes, and resistome risks in urban lakes of different trophic states: Internal links and external influences

Anthropogenic discharge of nutrients, metals, and antibiotics poses multiple threats to the health of aquatic ecosystems and humans, e.g., causing eutrophication, and introduction of resistance genes into human pathogens. The potential link between microbial communities, resistance genes, and eutrophication levels in urban lakes is complex and remains unclear, which is crucial for ecological and human health risk assessment. Here, five urban lakes of different trophic conditions were investigated to quantify their microbial diversity, and high-resolution profiles of antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) were established. Metagenome and multivariance analyses indicated that the microbial structures, distribution of resistance genes and mobile genetic elements (MGEs), and virulence factor genes (VFGs) significantly differed between the lakes. The hypereutrophic lake Nanhu harbored the lowest microbial diversity but the highest level of resistance genes. Microbial communities and MGEs were identified as the main drivers in shaping the profiles of ARGs and MRGs, while external environmental factors played an indirect role in the changing resistance genes. Two members of Proteobacteria, Aestuariivirga and Limnohabitans were identified as predominant bacterial hosts of ARGs in most samples. In addition, the resistome risk scores were found positively correlated with water quality factors and negatively correlated with microbial diversity in the urban lakes. Our study provides novel insights into the link between microbial diversity, MGEs, and the potential dissemination risk of ARGs in urban lakes.