Abstract
BACKGROUND: Terrestrial hot springs are extreme environments shaped by geothermal heat, geogenic gases and extremes of pH and temperatures. Their gas fluxes, which include CO(2), CO, H(2)S and SO(2), mirror the chemical composition of CO(2)-rich waste streams. Microbial communities inhabiting these environments are typically thermotolerant or thermophilic and sustained by CO(2) fixation and chemolithotrophic metabolism. Such communities may therefore provide a natural starting point for developing ex-situ, consortium-based biotechnologies capable of operating under elevated temperatures and chemically harsh conditions. Here, we assess the metabolic capabilities of hot spring microbiomes systematically through a biotechnological lens. RESULTS: We conducted comparative analysis of 73 worldwide hot spring metagenomes, spanning a wide range of environmental conditions (pH 1.5-10.0, temperatures 25-98 °C). By taking a gene-centric approach to whole communities, we show that hot spring microbiomes ubiquitously encoded carbon fixation pathways and biosynthetic genes (and gene clusters) for the synthesis of value-added products, regardless of geographical location and pH-temperature conditions. Candidate value-added products include platform chemicals such as acetone, lactic acid, and 1,2-propanediol, as well as high-value biomolecules including B vitamins and alginate. CONCLUSIONS: This first biotechnology-focused assessment of hot spring microbiomes demonstrates that these communities encode the genomic potential to support novel, ex situ microbial platforms for upgrading CO(2) and transforming chemically complex gas mixtures. SIGNIFICANCE: Industrial CO(2) waste streams pose both an environmental challenge and an unutilised resource. Harnessing microbial consortia to valorise CO(2), through a circular bioeconomy, remains underexplored and could offer an alternative to energy-intensive chemical methods. By reanalysing predominantly publicly available metagenomic data, we demonstrate how hot spring microbiomes can be mined for traits pre-adapted to CO(2)-rich, high-temperature, and chemically extreme conditions. In doing so, we provide proof-of-concept for their future biotechnological application and establish a blueprint for other microbiome-scale bioprospecting surveys.