Extreme microbial longevity and preparations for Exo Mars

Halite was discovered in the SNC meteorites, which stem from Mars, and recently by the rovers on the Martian surface; together with the previous isolation of several viable halobacteria (haloarchaea) from Permian rock salt, which is believed to be 250 millions years old, a re-consideration of microbial survival conditions and the possibility of preservation for very long time periods appears warranted. The data which are expected from this project should strengthen the plans to include a specific search for halophilic microorganisms into the efforts to discover extraterrestrial life. One main objective of this proposal is the elucidation of potential strategies of haloarchaea for long term survival; this could lead to the recognition of molecules and/or genes which are associated with the state of dormancy. Selected haloarchaea (mainly novel isolates from rock salt) will be examined for starvation responses, such changes in membrane status and composition of their proteome, alterations in morphology, size and aggregation status. The influence of factors in the rock salt on growth and morphology will also be examined. Another approach is the embedding of haloarchaea in salt crystals under nearly natural evaporation conditions. Previous results showed the localization of cells in fluid inclusions, which could be demonstrated by staining cells with fluorescent dyes prior to embedding. Several haloarchaea were found to undergo morphological changes, mainly a transformation to spherical forms, upon embedding in salt crystals. The properties of these spheres, including their resistance to environmental stresses and gamma radiation, will be investigated. The results will form the basis for the contribution to the planned Pasteur Payload of the ESA ExoMars mission. The GENTNER instruments, which include a highly sensitive Raman spectrometer, are being developed by a European consortium. The second goal of this proposal consists in the development of strategies for the preparation of suitable testing material, which can be used with the GENTNER instruments. Halite-embedded microorganisms will be subjected to Raman spectrometry to evaluate the minimum amount of detectable cells, the influence of growth phase and other parameters. Preparation of testing material will also be performed in a simulated Martian environment, which is available in the Mars chamber at the Austrian Academy of Science in Graz.

Halite was discovered in the SNC meteorites, which stem from Mars, and recently by the rovers on the Martian surface; together with the previous isolation of several viable halobacteria (haloarchaea) from Permian rock salt, which is believed to be 250 millions years old, a re-consideration of microbial survival conditions and the possibility of preservation for very long time periods appears warranted. The data which are expected from this project should strengthen the plans to include a specific search for halophilic microorganisms into the efforts to discover extraterrestrial life. One main objective of this proposal is the elucidation of potential strategies of haloarchaea for long term survival; this could lead to the recognition of molecules and/or genes which are associated with the state of dormancy. Selected haloarchaea (mainly novel isolates from rock salt) will be examined for starvation responses, such changes in membrane status and composition of their proteome, alterations in morphology, size and aggregation status. The influence of factors in the rock salt on growth and morphology will also be examined. Another approach is the embedding of haloarchaea in salt crystals under nearly natural evaporation conditions. Previous results showed the localization of cells in fluid inclusions, which could be demonstrated by staining cells with fluorescent dyes prior to embedding. Several haloarchaea were found to undergo morphological changes, mainly a transformation to spherical forms, upon embedding in salt crystals. The properties of these spheres, including their resistance to environmental stresses and gamma radiation, will be investigated. The results will form the basis for the contribution to the planned Pasteur Payload of the ESA ExoMars mission. The GENTNER instruments, which include a highly sensitive Raman spectrometer, are being developed by a European consortium. The second goal of this proposal consists in the development of strategies for the preparation of suitable testing material, which can be used with the GENTNER instruments. Halite-embedded microorganisms will be subjected to Raman spectrometry to evaluate the minimum amount of detectable cells, the influence of growth phase and other parameters. Preparation of testing material will also be performed in a simulated Martian environment, which is available in the Mars chamber at the Austrian Academy of Science in Graz.