[biorxiv.org] The Eboliang Hu saline lakes in the hyper-arid Qaidam Basin is a high-altitude, weakly acidic hypersaline system with strong environmental gradients and limited nitrogen availability.
To resolve its microbial ecology and evolutionary context, we performed genome-resolved metagenomic sequencing across four distinct habitats, reconstructing 46 medium- to high-quality metagenome-assembled genomes (MAGs) and a comprehensive gene catalog. The community shows pronounced spatial heterogeneity and is dominated by Thermodesulfobacteriota, Pseudomonadota, Bacteroidota, and archaeal lineages.
Phylogenomic placement and large-scale sequence comparisons indicate that multiple dominant taxa exhibit affinity to marine- and subsurface-associated reference lineages, consistent with long-term isolation of a marine-derived ecosystem about 10–11 million years ago.
Functional reconstruction reveals a distributed metabolic system in which carbon, nitrogen, and sulfur cycling are partitioned across taxa. Notably, hydrogen oxidation and arsenite oxidation are recurrent energy-producing strategies across dominant lineages, indicating redox flexibility under oligotrophic conditions.
Comparative genomics further suggests lineage-specific adaptations to osmotic stress, UV exposure, and nutrient limitation. Horizontal gene transfer and phylogenetic incongruence among key metabolic genes indicate that co-evolutionary processes and gene exchange have contributed to functional innovation.
These findings provide a framework for understanding microbial persistence and evolution in isolated extreme environments and offer potential analogs for extraterrestrial habitability.
Maximum-likelihood phylogenomic tree of the 46 recovered MAGs and 64 reference genomes. The tree integrates 46 MAGs (high-quality MAGs shown in green; medium-quality MAGs shown in orange) and 64 reference genomes from the NCBI Genome database (gray). A heatmap adjacent to the tree displays the relative abundance of each MAG across samples S1-S4. The environmental origins of the closest reference genomes to dominant MAGs are annotated. A boxplot compares estimated genome sizes between MAGs affiliated with Thermodesulfobacteriota and Bacteroidota (estimated genome size = assembled MAG length / CheckM completeness). — biorxiv.org
Astrobiology,
