Microbial Communities, Resistome Risk and Nitrogen Metabolism‐Related Genes in Particle‐Attached and Free‐Living Microbial Fractions of Yunnan‐Guizhou Plateau Lakes

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ABSTRACT Plateau freshwater lakes are ecologically sensitive ecosystems that provide valuable opportunities to study relationships among microbial diversity, antibiotic resistance genes (ARGs), and nitrogen metabolism in aquatic environments. In this study, we investigated whether microbial community composition, resistance profiles, and nitrogen transformation functions are associated in freshwater lakes of the Yunnan‐Guizhou Plateau. This study analysed microbial community structure and functional diversity in eight freshwater lakes, with explicit comparisons between particle‐attached (PA) and free‐living (FL) microbial lifestyles. ARG profiles were characterised using metagenomic sequencing and bioinformatics analyses, and co‐occurrence patterns among ARGs, mobile genetic elements (MGEs), and nitrogen metabolism‐related genes were statistically evaluated. Particle‐attached microorganisms exhibited significantly higher community diversity, whereas free‐living fractions showed higher functional gene diversity, indicating clear niche partitioning between microbial lifestyles. Multiresistance genes, macrolide‐lincosamide‐streptogramin (MLS) resistance genes, and tetracycline resistance genes constituted the dominant resistance spectrum across the studied lakes. MGEs were strongly positively correlated with ARG abundance. Dissimilatory nitrate reduction to ammonium (DNRA) was the dominant nitrogen transformation pathway, and DNRA‐related genes were significantly positively correlated with ARGs. Members of Gammaproteobacteria were identified as major taxa associated with both DNRA‐related genes and ARGs. These results demonstrate previously underappreciated associations between antibiotic resistance and nitrogen‐cycling functions in Plateau freshwater lakes. In particular, the consistent correlations between ARGs and DNRA‐related genes suggest a potential ecological linkage between these functions, although the underlying mechanisms remain unclear. Our findings highlight the importance of evaluating antimicrobial resistance risks in freshwater ecosystems within their broader biogeochemical context.

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