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The SPORES experiment of the EXPOSE-R mission: Bacillus subtilis spores in artificial meteorites

  • Corinna Panitz (a1) (a2), Gerda Horneck (a1), Elke Rabbow (a1), Petra Rettberg (a1), Ralf Moeller (a1), Jean Cadet (a3), Thierry Douki (a3) and Guenther Reitz (a1)...


The experiment SPORES ‘Spores in artificial meteorites’ was part of European Space Agency's EXPOSE-R mission, which exposed chemical and biological samples for nearly 2 years (March 10, 2009 to February 21, 2011) to outer space, when attached to the outside of the Russian Zvezda module of the International Space Station. The overall objective of the SPORES experiment was to address the question whether the meteorite material offers enough protection against the harsh environment of space for spores to survive a long-term journey in space by experimentally mimicking the hypothetical scenario of Lithopanspermia, which assumes interplanetary transfer of life via impact-ejected rocks. For this purpose, spores of Bacillus subtilis 168 were exposed to selected parameters of outer space (solar ultraviolet (UV) radiation at λ>110 or >200 nm, space vacuum, galactic cosmic radiation and temperature fluctuations) either as a pure spore monolayer or mixed with different concentrations of artificial meteorite powder. Total fluence of solar UV radiation (100–400 nm) during the mission was 859 MJ m−2. After retrieval the viability of the samples was analysed. A Mission Ground Reference program was performed in parallel to the flight experiment. The results of SPORES demonstrate the high inactivating potential of extraterrestrial UV radiation as one of the most harmful factors of space, especially UV at λ>110 nm. The UV-induced inactivation is mainly caused by photodamaging of the DNA, as documented by the identification of the spore photoproduct 5,6-dihydro-5(α-thyminyl)thymine. The data disclose the limits of Lithopanspermia for spores located in the upper layers of impact-ejected rocks due to access of harmful extraterrestrial solar UV radiation.


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Becker, R.H. & Pepin, R.O. (1984). The case for a Martian origin of the shergottites: nitrogen and noble gases in EETA 79001. Earth Planet. Sci. Lett. 69, 225242.
Clark, B.C. (2001). Planetary interchange of bioactive material: probability factors and implications. Orig. Life Evol. Biosph. 31, 185197.
Demets, R. et al. (2014). Window contamination on EXPOSE-R. Int. J. Astrobiol.
Douki, T., Court, M., Sauvaigo, S., Odin, F. & Cadet, J. (2000). Formation of the main UV-induced thymine dimeric lesions within isolated and cellular DNA as measured by high performance liquid chromatography-tandem mass spectrometry. J. Biol. Chem. 275, 1167811685.
Dreibus, G. & Wänke, H. (1984). Accretion of the Earth and the Inner Planets. In Proc. 27th Int. Geological Congress, Geochemistry and Cosmochemistry, vol. 11, pp. 120. VNU Science Press, Utrecht.
Dreibus, G. & Wänke, H. (1985). Mars, a volatile-rich planet. Meteoritics 20, 367381.
Eugster, O., Herzog, G.F., Marti, K. & Caffee, M.W. (2006). Irradiation records, cosmic-ray exposure ages, and transfer times of meteorites. In Meteorites and the Early Solar System II, ed. Lauretta, D.S. & McSween, H.Y., pp. 829851. The University of Arizona Press, Tucson, USA.
Facius, R., Bücker, H., Hildebrand, D., Horneck, G., Höltz, G., Reitz, G., Schäfer, M. & Toth, B. (1978). Radiobiological results from the Bacillus subtilis Biostack experiments within the Apollo and the ASTP spaceflights. Life Sci. Space Res. 16, 151156.
Gladman, B.J., Burns, J.A., Duncan, M., Lee, P. & Levison, H.F. (1996). The exchange of impact ejecta between terrestrial planets. Science 271, 13871392.
Horneck, G., Bücker, H. & Reitz, G. (1994). Long-term survival of bacterial spores in space. Adv. Space Res. 14, (10)4145.
Horneck, G., Rettberg, P., Reitz, G., Wehner, J., Eschweiler, U., Strauch, K., Panitz, C., Starke, V. & Baumstark-Khan, C. (2001). Protection of bacterial spores in space, a contribution to the discussion on panspermia. Orig. Life Evol. Biosph. 31, 527547.
Horneck, G. et al. (2008). Microbial rock inhabitants survive impact and ejection from host planet: first phase of lithopanspermia experimentally tested. Astrobiology 8, 1744.
Horneck, G., Klaus, D.M. & Mancinelli, R.L. (2010). Space microbiology. Microbiol. Mol. Biol. Rev. 74, 121156.
Horneck, G., Moeller, R., Cadet, J., Douki, T., Mancinelli, R.L., Nicholson, W.L., Panitz, C., Rabbow, E., Rettberg, P., Spry, A., Stackebrandt, E., Vaishampayan, P. & Venkateswaran, K.J. (2012). Resistance of bacterial endospores to outer space for planetary protection purposes – experiment PROTECT of the EXPOSE-E mission. Astrobiology 12, 445456.
Melvin, T., Cunniffe, S.M., O'Neill, P., Parker, A.W. & Roldan-Arjona, T. (1998). Guanine is the target for direct ionisation damage in DNA, as detected using excision enzymes. Nucleic Acids Res. 26, 49354942.
Mileikowsky, C., Cucinotta, F., Wilson, J.W., Gladman, B., Horneck, G., Lindegren, L., Melosh, J., Rickman, H., Valtonen, M. & Zheng, J.Q. (2000). Natural transfer of viable microbes in space, Part 1: from Mars to Earth and Earth to Mars. Icarus 145, 391427.
Moeller, R., Horneck, G., Rettberg, P., Mollenkopf, H.-J., Stackebrandt, E. & Nicholson, W.L. (2006). A method for extracting RNA from dormant and germinating Bacillus subtilis strain 168 endospores. Curr. Microbiol. 53, 227231.
Moeller, R., Douki, T., Cadet, J., Stackebrandt, E., Nicholson, W.L., Rettberg, P., Reitz, G. & Horneck, G. (2007). UV-radiation-induced formation of DNA bipyrimidine photoproducts in Bacillus subtilis endospores and their repair during germination. Int. Microbiol. 10, 3946.
Moeller, R., Rohde, M. & Reitz, G. (2010). Effects of ionizing radiation on the survival of bacterial spores in artificial Martian regolith. Icarus 206, 783786.
Nicholson, W.L. (2009). Ancient micronauts: interplanetary transport of microbes by cosmic impacts. Trends Microbiol. 17, 243250.
Nicholson, W.L. & Setlow, P. (1990). Sporulation, germination and outgrowth. In Molecular Biological Methods for Bacillus, ed. Harwood, C.R. & Cuttings, S.M., pp. 391450. John Wiley and Sons, Inc., Chichester, UK.
Nicholson, W.L., Munakata, N., Horneck, G., Melosh, H.J. & Setlow, P. (2000). Resistance of Bacillus endospores to extreme terrestrial and extraterrestrial environments. Microb. Mol. Biol. Rev. 64, 548572.
O'Keefe, J.D. & Ahrens, T.J. (1986). Oblique impact: a process for obtaining meteorite samples from other planets. Science 234, 346349.
Onofri, S. et al. (2012). Survival of rock-colonizing organisms after 1.5 years in outer space. Astrobiology 12, 508516.
Rabbow, E. et al. (2014). The astrobiological mission EXPOSE-R on board of the International Space Station. Int. J. Astrobiol.
Scalzi, G., Selbmann, L., Zucconi, L., Rabbow, E., Horneck, G., Albertano, P. & Onofri, S. (2012). LIFE experiment: isolation of cryptoendolithic organisms from Antarctic colonized sandstone exposed to space and simulated Mars conditions on the International Space Station. Orig. Life Evol. Biosph. 42, 253262.
Vickery, A.M. & Melosh, H.J. (1987). The large crater origin of SNC meteorites. Science 237, 738743.
Wassmann, M. et al. (2012). Survival of spores of the UV-resistant Bacillus subtilis strain MW01 after exposure to Low-Earth Orbit and simulated Martian conditions: data from the space experiment ADAPT on EXPOSE-E. Astrobiology 12, 498507.
Wasson, J.T. & Wetherill, G.W. (1979). Dynamical, chemical and isotopic evidence regarding the formation locations of asteroids and meteorites. In Asteroids, University, ed. Gehrels, T., pp. 926974. Arizona Press, Tucson.


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The SPORES experiment of the EXPOSE-R mission: Bacillus subtilis spores in artificial meteorites

  • Corinna Panitz (a1) (a2), Gerda Horneck (a1), Elke Rabbow (a1), Petra Rettberg (a1), Ralf Moeller (a1), Jean Cadet (a3), Thierry Douki (a3) and Guenther Reitz (a1)...


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