187 / 2025-04-14 13:33:32

Living Against Extremes: Microbial Communities in the Polyextreme Qaidam Basin Desert

Qaidam Basin,extreme environments,Mars analog,extremophiles,adaptive strategies

Theme 4: Microbial and Biogeochemical Evolution through Time > Session 4b: Roles of Microbes in Shaping Our Habitable Earth

The Qaidam Basin in the northern Qinghai-Tibet Plateau is one of the driest and highest deserts on Earth. The polyextreme conditions of the basin, including hyperaridity, hypersalinity, and high UV radiation, along with widespread evaporites and Mars-like landforms, make it a unique terrestrial analog for Mars. Life becomes scarce and loses diversity due to the extreme environments, and microorganisms drive the key biogeochemical processes in the Qaidam Basin. Using metagenomic sequencing and culture-dependent methods, we investigated microbial diversity, function, distribution, and adaptive strategies in this hyperarid desert. Our results revealed that microbial communities were predominantly composed of Actinobacteriota and Proteobacteria. Soil physicochemical characteristics, such as water content, total organic carbon (TOC) content, and pH, significantly impacted the distribution and function of microbial communities. Translucent rocks could provide subsurface refuge niches for microorganisms, supporting self-sustaining micro-ecosystems where Cyanobacteria play important roles as primary producers. Furthermore, the Qaidam Basin regolith was exposed to Earth’s near space at an altitude of ~35 km, and four survival bacterial strains were isolated after exposure. Functional annotation revealed the metabolic versatility of prokaryotic communities in the Qaidam Basin, exhibiting diverse potentials for carbon, hydrogen, nitrogen, sulfur, and chlorine metabolic capabilities. Trace gases (e.g., CO and H₂) could serve as significant energy sources for microbial respiration in these nutrient-deprived environments. Multiple stress response genes against DNA damage, oxidative stress, and osmotic stress, along with the presence of pathways for the biosynthesis and uptake of compatible solutes may contribute to microbial resistance under polyextreme conditions. These findings of microbial diversity, metabolic potential, and adaptive strategies in the Mars-like Qaidam Basin provide insights into the limits of life on Earth and the detection of potential biosignatures on Mars.