The impact of martian chemistry on the metabolism of methanogenic archaea

There is evidence that water may exist on Mars in the form of brines. The chemistries of these brines will be greatly influenced by the local lithologies, which would, in turn, impact on the organisms that could survive there . Four geological analogues were developed based on four broad martian lithologies: a global composition, an early and unaltered basaltic composition, a sulfur rich composition and a haematite rich composition (see talk by Ramkissoon et al., this conference, for further details). These analogues, and the brines derived from them, will be used to simulate the martian environment and will be inoculated with three species of methanogenic archaea to examine the impacts on their growth and metabolism. Methanogenic archaea represent model organisms for attempting to characterize martian life. A hydrogenotrophic metabolism enables them to survive through autotrophic growth on carbon dioxide. Three species of methanogenic archaea were selected to be used in a series of simulation experiments to evaluate the potential habitability of potential aqueous subsurface environments on Mars. Of the selected species, all have been shown to have a robust temperature and pH tolerance. Furthermore, Methanosarcina soligelidi SMA-21 is highly resistant to desiccation, starvation and ultraviolet radiation and has been shown to grow under martian simulation conditions; Methanobacterium arcticum M2 is able to tolerate high concentrations of perchlorate. In this poster, we will present details of how these organisms will be inoculated into brines derived from the martian regolith analogues and how survivability, growth and alterations in metabolism of these species will be assessed following incubation