Trace gas oxidation by soil bacteria surrounding a Polloquere hot spring

High-elevation arid regions harbor microbial communities reliant on metabolic niches and flexibility to survive. The oxidation of atmospheric trace gases, namely hydrogen (H2) and carbon monoxide (CO), serves as a widespread tactic for organisms in these environments to drive aerobic respiration and, occasionally, carbon fixation under nutrient-limited conditions. In this study, we assessed whether proximity to Polloquere, a geothermal spring in an arid Andean salt flat, affects the metabolic structure and trace gas-oxidation potential of nearby soil microbial populations. Rates of atmospheric H2 and CO uptake were shown to increase with radial distance from the spring despite a drastic decline in biomass. Kinetic estimates suggest that gas emission from Polloquere enriches the local environment with trace gases, resulting in decreased substrate affinity for H2 and CO compared to similar environments. Metagenomic analyses revealed a shift in the metabolic landscape from the spring-adjacent to distal soils, with trace gas-oxidizers becoming increasingly prevalent and phylogenetically diverse as the soils leave the influence of the hot spring. These results indicate that Polloquere represents a "microbial oasis" within the salar, hosting divergent communities across a restricted spatial scale and potentially acting as a model ecosystem for other geothermal systems in desert environments.