Salinity and ionic composition drive prokaryotic community assembly in Tuolekule Lake, China

Saline lakes in arid and semi-arid regions are home to unique ecosystems characterized by high salinity and alkalinity, as well as extreme environmental stresses. Despite these harsh conditions, they support diverse extremophilic microbial communities with distinct structures, offering substantial biomedical and biotechnological potential. Tuolekule Lake is a hypersaline, alkaline lake situated in a closed basin in the northern foothills of the East Tianshan Mountains in Xinjiang, China. This high-altitude extreme environment constitutes a distinct ecosystem. However, the structure of its microbial communities, their environmental drivers and their biotechnological potential remain largely unexplored. This study systematically analyzed the physicochemical properties of sediment samples from Tuolekule Lake. Subsequently, high-throughput sequencing identified a strong association between environmental factors and microbial community structure, paving the way for the targeted cultivation of microorganisms based on these insights. Results revealed that the sediments are dominated by Cl⁻, SO₄²⁻, Na⁺, and Mg²⁺ ions, confirming the lake's classification as a sulfate-chloride type. Salinity, SO₄²⁻ concentration, and pH emerged as the key environmental factors structuring the microbial community, predominantly composed of Pseudomonadota, Halanaerobiaeota, and Bacteroidota. Co-occurrence network analysis revealed distinct modular associations among taxa. Functional prediction based on 16S rRNA gene sequences for these communities indicated that chemoheterotrophy and fermentation served as putative core metabolic processes, alongside a significant enrichment of sulfur cycling pathways. These inferred metabolic capabilities collectively suggest potential adaptive strategies employed by the microbial community under extreme conditions. Building on these community insights, a targeted cultivation strategy was implemented, successfully isolating 54 halotolerant microbial strains and revealing the environment's rich reservoir of extremophilic microorganisms.