Impact Crater Hydrothermal Systems Support Rapid Microbial Enrichment and Diverse Metabolic Potential

Impact crater hydrothermal systems, formed after asteroid and comet impacts, have been proposed as promising habitats for life on early Earth and as key targets in the search for life on planetary bodies such as Mars, since they provide liquid water and active geochemical turnover. Because no newly formed impact structures exist on Earth, studies of microbial establishment in impact-crater hydrothermal systems have largely relied on the direct observation of fossil microbial life or its isotopic signatures. To address this limitation, we established simulated microcosm hydrothermal systems in the laboratory using melt-bearing impact breccia (suevite) from the Ries impact structure, Germany, and temperate soils. Within weeks, these systems hosted taxonomically diverse communities, with broad metabolic potential, partitioned among oxidized impact glass, endolithic suevite habitats, and sedimentary environments. Dominant taxa included thermophiles from primarily heterotrophic lineages (e.g., Meiothermus and Aneurinibacillus spp.), as well as lineages with potentially chemolithotrophic metabolisms (e.g., Brockia spp.). Metagenomic annotations identified genes associated with methane, iron, and sulfur cycling, including sulfate-reduction, indicating metabolic potential for biogeochemically relevant processes under hydrothermal conditions. These results show that impact-generated hydrothermal systems can rapidly support diverse thermophilic microbial communities with habitat-specific community structure and metabolic potential, supporting their relevance as analogue environments for studying early microbial establishment and biosignature formation in planetary impact settings.