Metabolomic Profile of the Fungus Cryomyces antarctiucus Under Simulated Martian and Space Conditions as Support for Life-Detecion Missions on Mars

The identification of traces of life beyond Earth (e.g., Mars, icy moons) is a challenging task because terrestrial chemical-based molecules may be destroyed by the harsh conditions experienced on extraterrestrial planetary surfaces. For this reason, studying the effects on biomolecules of extremophilic microorganisms through astrobiological ground-based space simulation experiments is significant to support the interpretation of the data that will be gained and collected during the ongoing and future space exploration missions. Here, the stability of the biomolecules of the ryptoendolithic black fungus Cryomyces antarcticus, grown on two Martian regolith analogues and on Antarctic sandstone, were analysed through a metabolomic approach, after its exposure to Science Verification Tests (SVTs) performed in the frame of the European Space Agency (ESA) Biology and Mars Experiment (BIOMEX) project. These tests are building a set of ground-based experiments performed before the space exposure aboard the International Space Station (ISS). The analysis aimed to investigate the effects of different mineral mixtures on fungal colonies and the stability of the biomolecules synthetised by the fungus under simulated Martian and space conditions. The identification of a specific group of molecules showing good stability after the treatments allow the creation of a molecular database that should support the analysis of future data sets that will be collected in the ongoing and next space exploration missions

Fungal Biomarkers Stability in Mars Regolith Analogues after Simulated Space and Mars-Like Conditions

The discovery of life on other planets and moons in our solar system is one of the most important challenges of this era. The second ExoMars mission will look for traces of extant or extinct life on Mars. The instruments on board the rover will be able to reach samples with eventual biomarkers until 2 m of depth under the planet’s surface. This exploration capacity offers the best chance to detect biomarkers which would be mainly preserved compared to samples on the surface which are directly exposed to harmful environmental conditions. Starting with the studies of the endolithic meristematic black fungus Cryomyces antarcticus, which has proved its high resistance under extreme conditions, we analyzed the stability and the resistance of fungal biomarkers after exposure to simulated space and Mars-like conditions, with Raman and Gas Chromatography–Mass Spectrometry, two of the scientific payload instruments on board the rover

Geomicrobiological characterization of Antarctic sandstones - Preliminary results

Antarctica supports some of the most unexplored and isolated ecosystems of the planet, wherein existence of life under the most extreme conditions is still being questioned. In the driest and coldest ice-free areas of continental Antarctica, the McMurdo Dry Valleys, the environmental conditions reach the limits for supporting life through endolithism. These regions are considered as a perfect testbed for astrobiological studies, supporting future exploration missions finalized to the search for life on other planets. In these areas, Antarctic sandstone is characterized by a peculiar colorization due to the stratification of microorganisms into a cryptoendolithic community [1]. An unfavorable change of environmental conditions results in death of the community, followed by the formation of a mummified microbial community [2]. Sandstone exhibits exfoliation mosaic patterns during the microorganisms' mummification process [3], as well as a reddish color on the top surface layer [2]. In the context of the ESA BioSigN project (BioSignatures and habitable Niches: experiment on the International Space Station) for investigating the habitability of Mars and icy moons as well as the stability and detection of biosignatures in general and in particular on microfossils), for the first time, we characterized Antarctic sandstone, sampled at Timber Peak locality (Northern Victoria Land), from a combined geomicrobiological point of view by merging different and complementary techniques. Raman and InfraRed spectroscopy analyses identified the presence of organic matter and functional groups associated with biological molecules at the observable reddish top surface layers, giving also an accurate mineralogy characterization. A confocal laser scanning fluorescence microscopy detected chitin remnants and the occurrence of eukaryotic microorganisms’ features (e.g. septa and anastomosing filaments), probably associated with fungal filaments. These findings were further supported by cultivation analyses, which allowed the isolation of several fungal morphologies. In association with spherical cell-like morphologies, similar structures were also discovered using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. References 1. Selbmann, L. et al. (2005)Stud Mycol, 51, 1-32. 2. Friedmann E.I and Weed, R. (1987) Science, 236, 703-705. 3. Sun, H. J. and Friedmann,E. I. (1999)Geomicrobiology Journal, 16, 193-202