Results on the survival of cryptobiotic cyanobacteria samples after exposure to Mars-like environmental conditions

Abstract

Tests on cyanobacteria communities embedded in cryptobiotic crusts collected in hot and cold deserts on Earth were performed under Mars-like conditions. The simulations were realized as a survey, to find the best samples for future research. During the tests organisms have to resist Mars-like conditions such as atmospheric composition, pressure, variable humidity (saturated and dry conditions) and partly strong UV irradiation. Organisms were tested within their original habitat inside the crust. Nearly half of the cryptobiotic samples from various sites showed survival of a substantial part of their coexisting organisms. The survival in general depended more on the nature of the original habitat and type of the sample than on the different conditions they were exposed to. The best survival was observed in samples from United Arab Emirates (Jebel Ali, 25 km SW of Dubai town) and from Western Australia (near the South edge of Lake Barley), by taxa: Tolypothrix byssoidea, Gloeocapsopsis pleurocapsoides, Nostoc microscopicum, Leptolyngbya or Symploca sp. At both places in salty desert areas members of the Chenopodiaceae family dominated among the higher plants and in the cryptobiotic crust cyanobacterial taxa Tolypothrix was dominant. These organisms were all living in salty locations with dry conditions most of the year. Among them Tolypothrix, Gloeocapsopsis and Symploca sp. were tested in Mars simulation chambers for the first time. The results suggest that extremophiles should be tested with taken into account the context of their original microenvironment, and also the importance to analyse communities of microbes beside single organisms.

Earth as a Tool for Astrobiology—A European Perspective

“…For example, microbial cryptoendolithic communities that colonize the pore spaces of sedimentary rocks in Antarctica and other deserts to avoid stressful environmental conditions (e.g. ultraviolet (UV) radiation, very low or very high temperatures and very dry conditions) have been studied (Friedmann and Ocampo 1976;Friedmann 1982;Jänchen et al 2014;de Vera et al 2014a). Eukaryotes (e.g.…”

“…The aim of LEO space simulation facilities is to approach as much as possible LEO pressure of down to 10 −7 Pa and, in particular the short wavelength solar UV and vacuum UV (VUV) radiation non-attenuated by an Earth ozone layer. For Mars, simulation temperatures between 198 K (−75°C) and 293 K (20°C) are applied (de Vera et al , 2014a(de Vera et al , 2014bKrala et al 2011;Schuerger et al 2013;Martin and Cockell 2015), approaching temperatures observed in equatorial to mid-latitudes on Mars (McEwen et al 2011;Head et al 2003). In parallel, atmospheric pressure of about 600 to 800 Pa with a Mars-like atmospheric composition of about 95% CO 2 , 2.7% N 2 , and 1% O 2 and traces of water is obtained.…”

“…In parallel, atmospheric pressure of about 600 to 800 Pa with a Mars-like atmospheric composition of about 95% CO 2 , 2.7% N 2 , and 1% O 2 and traces of water is obtained. The need of adequate radiation spectra approximating the solar UV regimes is mainly achieved using specific solar UV lamps Lorek and Koncz 2013;de Vera et al 2014ade Vera et al , 2014b. A special type of Mars simulation facility are wind tunnels for the simulation of Martian dust devils and dust storms to investigate correlated effects, in particular on landers and rovers hardware, but also for a better understanding of their effect on the Martian environment itself.…”

“…The solar spectra range as it appears on Mars can be simulated by the use of a Xe-lamp and the applied above mentioned environmental parameters as well as the humidity can be varied according to the programed daily cycles. It can be used in non-biological simulation experiments (in different disciplines such as planetary geology, astrobiology, environmental chemistry and materials science and sensor testing), and for biologically relevant experiments by using hardware, which performs in situ measurements during the simulation experiments (de Vera et al , 2014aVera et al , 2014b see Sect. 4.1.1 of the present manuscript).…”

“…The activity of tested samples can be measured in situ by specific sensor hardware applied during the simulation experiments in addition to the sensors, which are measuring the environmental conditions during the simulation experiments. For example, the degree of photosynthetic activity can be monitored and recorded during simulation conditions by a planetary and Mars adapted measurement device named Mini-PAM (Walz 1999;Lorek and Koncz 2013, 2014a, 2014b. Methane production of methanogens can be observed during Mars simulation experiments due to the use of specific optical hardware like laser spectroscopy and gives indirectly information on growth rates of methanogens during simulation experiments (Schirmack et al 2014).…”