Viable metabolisms in a simulated martian chemical environment

Macey, Michael C.; Ramkissoon, Nisha K.; Pearson, Victoria K.; Schwenzer, Susanne P. and Olsson-Francis, Karen (2018). Viable metabolisms in a simulated martian chemical environment. In: AbGradE Symposium 2018, 22-24 Sep 2018, Berlin.



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 which are theroretically viable under martian chemical conditions. In order to better establish which of these are capable of supportung growth under martian conditions, we performed a series of enrichments using four previously developed 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 collected from Pyefleet mudflats in the Colne estuary (Essex, UK), rich in sulphate-reducing bacteria and methanogens. 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 of at 1 bar pressure and incubated for twenty days. The enrichments were 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 enirchment.

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