Microbiome of two isolated saline lakes in a Mars-like desert of the Qinghai–Tibet Plateau

Eboliang Hu is a mildly acidic saline-lake system in the hyper-arid Qaidam Basin, with hydrochemical gradients and little oxidized nitrogen. Metagenomics of four sampling sites yielded 46 medium- to high-quality metagenome-assembled genomes and a 937,632-gene catalog. Communities were heterogeneous; > 30% of 16S rRNA fragments at two sites lacked SILVA database matches above 97% identity. Phylogenies with extensive taxon-specific references placed abundant 16S rRNA lineages and several dominant genomes within marine-associated clades. The youngest same-species divergence estimate for Marinobacter guineae was compatible with late Miocene basin reorganization, supporting a marine biogeographic legacy followed by lineage-specific evolution. Carbon-, nitrogen- and sulfur-cycling potential was partitioned among taxa; hydrogen- and arsenite-oxidation genes, osmoregulation and DNA repair recurred across genomes. Ninety-four putative horizontal gene transfers involved redox metabolism and genome maintenance. Together, these findings link biogeographic legacy, metabolic complementarity and gene exchange to persistence in isolated saline systems and inform terrestrial Mars-analogue research.