Vertical stratification and distribution patterns of the ARG resistome in Fuxian Lake: Insights from a global...

Deep lakes are critical reservoirs for antibiotic resistance genes (ARGs), yet global ARG dynamics and vertical mechanisms remain poorly constrained. By combining metagenomics with a global comparative analysis across 17 plateau lakes and 83 Fuxian Lake samples, this study investigates ARG distribution from macro- to micro-scales. The macro-scale analysis identified Longitude, Latitude, and Temperature (all p-values < 0.05) as dominant constraints on ARG abundance. A distinct, synergistic mechanism drives vertical stratification: ARG enrichment occurs in the deep layer (50-150 m) at the lake center, but enrichment shifts to the shallow layer (0-40 m) in the tourism area. This complex pattern is governed by a biotic-abiotic synergy. Specifically, ARG dynamics in the deep layer are jointly regulated by biotic factors and physicochemical constraints such as pH and ORP. Differences observed at the local scale, including the increase in ARG abundance and rare-to-core conversion, contrast with broader patterns observed across plateau lakes. This study provides the first global distribution spectrum of ARGs in plateau lakes and reveals crucial interactive patterns. The persistent presence of high-risk ARGs and critical priority pathogens necessitates heightened vigilance. We propose controlling anthropogenic inputs and mitigating the risk of deep sediment pollutant release as crucial strategies for these vital freshwater resources.