Diversity and transmission processes of potentially pathogenic bacterial communities in the East Rongbuk Glaciers,...

Glacier retreat driven by global warming is releasing previously sequestered microbial communities, including potential human pathogens, into downstream environments. However, the diversity, ecological assembly mechanisms, and dispersal processes of these bacteria remain largely unknown in high-altitude glacier systems. In this study, we characterized potential pathogenic bacterial communities along a 1200 m elevation gradient (5293-6476 m) on the East Rongbuk Glacier, northern slope of Mount Everest, using high-throughput 16S rRNA gene sequencing for snow, ice, cryoconite, and moraine samples. A total of 833 pathogenic bacterial species were identified, with Proteobacteria and Cyanobacteria dominating the communities. Distinct altitude-dependent variations were observed, with taxa such as Paracoccus_yeei and Sphingomonas_paucimobilis enriched at high elevations. Canonical correspondence analysis indicated that geographic (e.g., altitude, latitude) and environmental variables (e.g., total carbon, organic carbon) significantly influenced community structure. β-nearest taxon index (βNTI) and generalized additive models (GAMs) revealed that both deterministic and stochastic processes governed community assembly. Network analysis suggested that non-pathogenic taxa with high modularity and centrality may suppress potential pathogens through ecological interactions. Source Tracker analysis demonstrated frequent microbial exchange among glacier habitats, with moraine and cryoconite acting as dominant sources. Certain pathogenic taxa showed clear signatures of downstream migration, highlighting the potential risk of glacier-derived pathogen dissemination via meltwater and aeolian processes. This study provides a comprehensive assessment of the diversity, drivers, and dispersal of potential pathogenic bacteria in a high-altitude glacier ecosystem, offering new insights into their ecological dynamics and informing future risk assessments under climate change scenarios.