THE SPACE EXPERIMENTS BOSS AND BIOMEX ON THE EXPOSE R-2 MISSION: FIRST RESULTS ON DESERT CYANOBACTERIA UNDER SPACE AND MARTIAN SIMULATIONS

摘要

The proposed space experiments BOSS (Biofilm Organisms Surfing Space) and BIOMEX (BIOlogy and Mars experiment) will take place on the space exposure facility EXPOSE-R2 on the International Space Station (ISS), which will be presumably launched in 2013. In BOSS the hypothesis is tested that microorganisms grown as biofilms, hence characterized by cells embedded and aggregated in their EPS matrix, are more tolerant to space and Martian conditions compared to their planktonic counterparts. Different microbial biofilms have been developed including those obtained by using strains of the cyanobacterium Chroococcidiopsis isolated from hot and cold deserts. While the prime objective of BIOMEX is to evaluate to what extent biomolecules, such as pigments and cellular components, are resistant to and can maintain their stability in space and under Mars-like conditions. The investigated samples consist of a variety of pigments, cell wall components from lichens, archaea, bacteria, cyanobacteria, snow and permafrost algae, black fungi and bryophytes. Results will be relevant for the formation of a biosignature data base; e.g. a Raman spectral library to be used when searching for extraterrestrial life biosignatures. The secondary objective is to investigate the endurance of extremophiles, focusing on their interactions with Moon and Mars analogues. Ground-based studies are currently carried out in the frame of EVTs (Experiment Verification Tests) by exposing the selected organisms to space and Martian simulations (e.g. temperatures, UV dosage and Mars-like CO_2 atmosphere). Results from the EVTs along with the experimental approaches used, performed on desert strains of Chroococcidiopsis in the frame of BOSS and BIOMEX, will be presented as a proof of concept on two selected parameters: UV-C irradiations and space vacuum. Results from the growth capability of the exposed samples, the integrity of their genomic DNA and permanence of the photosynthetic pigments, suggest the endurance of Chroococcidiopsis biofilms under simulated space and Martian conditions and support its employment as model prototroph to identify biosignatures for future life detection missions.