There is evidence that water may exist on Mars as brines in the subsurface. The chemistries of these brines will be greatly influenced by the local lithologies, which would impact on the organisms that could potentially live within them. There are multiple metabolisms that are theoretically viable under martian chemical conditions. In order to better establish which of these are capable of supporting persistent growth under martian conditions, we performed a series of enrichments using four geological simulants for Mars: a global composition, an early and unaltered basaltic composition, a sulfur-rich composition, and a haematite-rich composition. Enrichments were inoculated with sediment from Pyefleet mudflats in the Colne estuary (Essex, UK). Mudflat sediment was added to the simulant materials and a brine based on the chemistry of Rocknest. Enrichments were supplied with a H2/CO2 headspace at 1 bar pressure and incubated for 20 days. The enrichments were repeatedly subcultured into fresh simulant material and brines in order to effectively select for a community actively growing in this chemical environment. The enriched community was characterised through the isolation and identification of microbes, microscopy and the amplicon sequencing of 16S rRNA genes amplified from DNA extracted from each stage of the enrichment. Biotic and abiotic experiments were conducted to identify geochemical changes that occur due to the presence of microbial activity. We will present details on the communities enriched on the different martian simulants, metabolisms identified as present within the actively growing community and geochemical changes that were identified.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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