oa DEvelopment of a Cold Plasma Process to Isolate Archaeal LIPID Biomarkers In Halite Fluid Inclusions

Lipid membrane adaptations under extreme salinity conditions are essential to maintain cellular integrity and metabolic processes in Halobacterium. salinarum. We aim to study the mechanisms of adaptation of the lipidome of the archaeal H. salinarum to hypersaline conditions during halite crystal formation, which will provide key information on the potential preservation of lipid biosignatures over geological time. It is essential to ensure that the lipids detected within the halite crystals are only those of H. salinarum and do not correspond to organic residues on the surface of the halites. To this end, we investigated the effectiveness of cold plasma in removing organic compounds potentially present on the surface of halites.

Whatever the conditions of the cold plasma treatment, the residual amount of archaeol, the main membrane lipid of H. salinarum, in the treated crystals vs. the untreated ones was in average less than 5%. This shows for the first time the efficiency of such a treatment in removing the archaeal cells at the surface of halite crystals. This protocol has now to be tested on crystals inoculated with H. salinarum both internally and externally to ensure that only the lipids entrapped within the inclusion are preserved after the treatment.