Abstract EANA2026-3

Located in the East African Rift Valley of SW Kenya, Lake Magadi is an alkaline, hypersaline lake recharged by hot springs. This site is of significant astrobiological interest, hosting environments identified as suitable analogues for hydrothermal settings on the Archaean Earth, Noachian Mars, and potentially Europa and Enceladus. Microbial ecosystems flourish amongst these hot springs, despite the presence of multiple environmental stressors, including high pH, temperatures, salinities and metal concentrations. The functional diversity and metabolic capabilities that enable microbial survival in this habitat are understudied, but present an untapped resource of palaeoecologically and biotechnologically relevant adaptations. Microbial taxa richness and metabolic pathways in these microbial mats are currently being characterised using shotgun metagenomics and organic stable isotope geochemistry in order to develop hypotheses concerning the adaptation strategies utilised by microbial life in the diverse environmental settings of Lake Magadi. Similar strategies may be required to survive on other bodies in our Solar System with evidence of hydrothermal activity. Furthermore, the Magadi basin offers a unique opportunity to investigate microbial biosignature preservation in both silica- and carbonate-rich environments. Preliminary studies have revealed the presence of organic matter within hydrothermally-influenced chert outcrops, indicating a potential microbial role in their formation. Furthermore, putative stromatolites, likely formed around palaeolake margins, have also been sampled from deposit around the lake shores. Both classes of geological samples, along with modern microbial mats, are being investigated using comparative microscopic, (micro)spectroscopic and geochemical techniques to reveal which biomolecules and relics of biomass survive diagenesis in these geologically distinct settings. This information has the potential to inform the interpretation of biosignatures in rocks from the early Earth (e.g. Archaean greenstone belts), and the detection of biosignatures in samples retrieved by future Mars sample return missions, providing an insight into biogeochemical signatures diagnostic of ancient microbial communities.