Microbial Interactions with Mars Crustal Mineral Materials: Mars-relevant Biosignatures and Their Preservation under Destructive Martian Environmental Constrains

Abstract

Our investigations of microbial-mineral interfaces with terrestrial and extraterrestrial materials have shown that geological/mineralogical environment massively dictates biomineralisation patterns and associated mineral biosignatures. The study of Mars-relevant biosignatures requires Mars-relevant mineral materials, because microbial biomineralization patterns differ drastically between microorganisms grown on Mars crustal minerals and microorganisms grown on other extraterrestrial and terrestrial mineral materials. We have recently resolved nanoscale interface of an ancient rock-eating microorganism with the oldest Martian crust from Noachian Martian breccia NWA 7034 (Black Beauty, ~4.5 Gyr old), and delivered a prototype of microbial life of pure Martian design to investigate Mars-relevant biosignatures (Milojevic et al., 2021, doi.org/10.1038/s43247-021-00105-x). A further important advancement towards biosignatures identification is the detection of microbial fingerprints on Mars minerals that are stable under Mars-like environmental conditions. A set of desiccated microbial cells grown on Mars crustal minerals has already been launched for 1 year outside the ISS and exposed to Mars-like conditions in frames of the Tanpopo-4 orbital mission (2022-2023). Upon retrieval of cells from the ISS, we have investigated microbial survivability in Mars-like environment. Furthermore, high-resolution electron microscopy and nano-analytical techniques have been applied to identify biosignaturesof microbial life on Martian materials preserved under the destructive Martian environmental constrains. Resolving the microbial-mineral interface with Mars crustal minerals under the influence of harsh Mars environment can bring us closer to identify traces of unicellular life for current and future life search missions. Assessing the biogenicity based on Martian materials and its preservation potential in drastic Mars environment is a critical analytical step for the detection of Mars-relevant biosignatures.