Putative Lipidomics of Titan's Subsurface Ocean

The likely subsurface ocean on Titan has gained much interest as an astrobiological target. While this subsurface ocean is expected to be more hospitable than Titans surface, where organic compounds have been observed, conditions are still in the extreme range. Titans ocean pressure begins at 200-300 MPa under the ice I crust, extending to 750 GPa at the core-ocean interface. Titans ocean is also cold, ~ -15C below the ice I crust to ~ 10C at the ocean-core boundary. These conditions will most certainly have an impact on the types and structures of lipid biosignatures that would be produced, if the ocean is inhabited. In order to think about the existence of molecular biomarker production typical of high pressure oceans, we must first answer the question; Can we reasonably expect life to cope with Titans subsurface temperatures and pressures? Our aim is to demonstrate that earth organisms can survive and build biomass in Titans subsurface conditions. We are currently testing the Gammaproteobacteria Shewanella oneidensis at different pressures (in the 150-750 MPa range), and we aim to test this strain at high pressure and low temperature (5C), to see how the organisms lipid bilayer responds and adapts to such environments. We intend to perform multi-omics analyses, as well as lipid analysis, at three benchmark pressures (150, 400, 750 MPa). We expect to see large changes in the lipid distribution and structure, as well as possible changes in protein structure.