Space Microbiology

Abstract

SUMMARY The responses of microorganisms (viruses, bacterial cells, bacterial and fungal spores, and lichens) to selected factors of space (microgravity, galactic cosmic radiation, solar UV radiation, and space vacuum) were determined in space and laboratory simulation experiments. In general, microorganisms tend to thrive in the space flight environment in terms of enhanced growth parameters and a demonstrated ability to proliferate in the presence of normally inhibitory levels of antibiotics. The mechanisms responsible for the observed biological responses, however, are not yet fully understood. A hypothesized interaction of microgravity with radiation-induced DNA repair processes was experimentally refuted. The survival of microorganisms in outer space was investigated to tackle questions on the upper boundary of the biosphere and on the likelihood of interplanetary transport of microorganisms. It was found that extraterrestrial solar UV radiation was the most deleterious factor of space. Among all organisms tested, only lichens (Rhizocarpon geographicum and Xanthoria elegans) maintained full viability after 2 weeks in outer space, whereas all other test systems were inactivated by orders of magnitude. Using optical filters and spores of Bacillus subtilis as a biological UV dosimeter, it was found that the current ozone layer reduces the biological effectiveness of solar UV by 3 orders of magnitude. If shielded against solar UV, spores of B. subtilis were capable of surviving in space for up to 6 years, especially if embedded in clay or meteorite powder (artificial meteorites). The data support the likelihood of interplanetary transfer of microorganisms within meteorites, the so-called lithopanspermia hypothesis.

Archaea in artificial environments: Their presence in global spacecraft clean rooms and impact on planetary protection

“…Low nutrient levels, low humidity, frequent cleaning and sterilization procedures pose a threat for all organisms thriving or living in these environments (Venkateswaran et al, 2001). Challenging the survival of microbes is one of the major aims of spacecraft-associated clean rooms: In terms of planetary protection, biological contamination on spacecraft flying to extraterrestrial points of interest has to be controlled (understood and reduced) in order to avoid compromising the integrity of the future life-detection missions on Mars, Titan or other solar bodies (see also : Horneck et al, 2010). As nowadays spacecraft cannot be sterilized ('baked') as a whole, a microbial quality control of each hardware item is tremendously important.…”

E

“…2 Exposure tray of the ES029 experiment, which was mounted on a cold plate in the cargo bay of SL 1 Exposure Facilities, Fig. 3 Exposure tray of the Exobiology Radiation Assembly (ERA), which was mounted on the EURECA platform (Credit: ESA, from Horneck et al 2010) also used to study the mineral decomposition and microbial survival during atmospheric reentry within the ▶ STONE experiments (Brandstätter et al 2008;Cockell et al 2007;de la Torre et al 2010). Advanced exposure facilities with up to four times the capacity of the ES029 experiment of SL 1 were developed by the ▶ European Space Agency (ESA) with the Exobiology Radiation Assembly (ERA) for the ▶ EURECA mission (Fig.…”

“…1 Tray of the exposure facility ERA with sample carriers and optical filters during assembly (Credit ESA, from Horneck et al 2010) • Free Flyer ▶ Biostack that studied the biological responses of different systems to the structured components of cosmic radiation, i.e., ▶ HZE particles (cosmic rays consisting of energetic nuclei with atomic number 3 or greater) and nuclear disintegration events (Reitz et al 1995;Horneck 2007;Horneck et al 2010) See Also …”

Cadmium uptake capacity of an indigenous cyanobacterial strain, Nostoc entophytum ISC32: new insight into metal uptake in microgravity-simulating conditions

“…As a matter of fact, space biology refers to research on understanding of biological mechanisms such as the role of gravity at the cellular/molecular levels, biological effects of the radiation, survival factors in the Earth's outer biosphere and applicable features of the use of proper micro-organisms in bioregenerative life support systems. Thus, micro-organisms that thrive in such extreme environmental conditions are highly regarded by space biology scientists (Horneck et al, 2010). Many studies have shown that changes in gravity can affect physiological characteristics, growth, metabolism reactions, toxin production and cyanobacterial structures.…”