Dynamics of microbial communities succession in freeze-thaw soils of the Yangbark Glacier, Muztagh Ata.

The freezing and melting of glaciers cause significant changes in environmental and ecological conditions, while microbial community succession reflects the direction and pace of ecosystem transformation. To investigate the ecological functions and adaptation mechanisms of microbial communities in glacial melt zones under extreme conditions, sampling points were established along the Yangbark Glacier, Muztagh Ata. The community succession of soil microorganisms was analyzed by using Illumina NovaSeq technology. A total of 46 phyla, 760 genera, and 371 bacterial species, along with 12 phyla, 246 genera, and 298 fungal species were identified. Bacterial abundance and diversity peaked at 200-300 m from the glacier tongue (B3, B4), while fungal richness was higher at 100 m (B2) and 400 m (B5). Proteobacteria, Bacteroidetes, and Actinobacteria dominated bacterial communities, while Firmicutes emerged as the third largest group in the most exposed 500-600 m (B6, B7). Most fungi remained uncategorized, with Ascomycota being the predominant known group. Functionally, bacteria primarily engaged in amino acid synthesis, potentially providing nutrients for pioneer plants and other microorganisms, while fungi predominantly exhibited saprophytic nutrition, promoting organic matter decomposition and soil formation. Co-occurrence network showed that the bacterial network was loose and more resistant to environmental disturbance. In summary, varying freeze-thaw durations significantly influence microbial community structure and functional specialization. Bacteria and fungi employ distinct strategies to co-adapt to habitat changes, jointly driving the early development and elemental cycling of this frontier ecosystem.