The impact of martian brine chemistry on the growth of microorganisms

Macey, Michael C.; Ramkissoon, Nisha K.; Schwenzer, Susanne P.; Pearson, Victoria K. and Olsson-Francis, Karen (2017). The impact of martian brine chemistry on the growth of microorganisms. In: 1st British Planetary Science Congress, 3-5 Dec 2017, Glasgow.



There is evidence that water may currently exist on Mars as brines. The chemistries of these brines will be greatly influenced by the local lithologies, which would, in turn, impact on the organisms that could potentially live within them. We have previously developed four geological simulants for Mars: a global composition, an early and unaltered basaltic composition, a sulfur-rich composition, and a haematite-rich composition. Thermochemical modelling was used to determine the composition of brines associated with the alteration of the simulants under Mars-analog conditions. In this study, we assess whether microbial life would grow in these brines under martian simulated conditions.

The organisms used in these growth experiments were selected to represent a broad range of metabolic capabilities with relevance to Mars: They include methanogenic archaea (Methanosarcina soligelidi, Methanobacterium arcticum and Methanothermococcus thermolithotrophicus), as biotic processes are a potential source of methane in the martian atmosphere. Additional organisms were species of iron reducing bacteria (Desulfosporomusa polytropa), due to the presence of iron oxides on Mars and the high amount of Fe3+ in haematite; iron oxidising bacteria (Acidovorax sp. BoFeN1), due to the high presence of Fe2+; and sulphate reducing bacteria (Desulfomicrobium macestii), due to the high sulfur content of Paso Robles. We will present details of the impact of the martian simulants on the growth and metabolism of the selected strains, which gives insight into habitability on early Mars.

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