August 1, 2012.
The definitive version is available at http://dx.doi.org/.
Increasing efforts to find and study habitable conditions and the possibility of life on extraterrestrial cosmic bodies have also deepened the need for planetary protection advancements to prevent possibilities of forward and backward contamination. Despite stringent precautions to ensure spacecraft cleanliness, a number of spore-forming bacteria, including the biofilm forming strain, Bacillus horneckiae have been isolated from spacecraft associated surfaces. B. horneckiae spores have demonstrated unusually high resistance to rigorous sterilization procedures, and extreme conditions, including intense UV radiation. This exceptionally high tolerance of extreme conditions demonstrated by spore-forming bacteria highlighted the need to assess the viability of these microbes in situ (in real) space. Thus, similar to prior EXPOSE projects commissioned by ESA, the BOSS (Biofilm Organisms Surfing Space) project aims to understand the mechanisms by which biofilm forming organisms, such as B. horneckiae, are potentially able to withstand harsh space conditions.
The objective of this study was to establish reference data on the survivability rates of B. horneckiae spores after exposure to certain ground-simulated space conditions: UV-space radiation, dark-space (no) UV radiation, simulated Martian UV, and simulated dark-Martian UV radiation. B. horneckiae spores were extracted from metal coupons using polyvinyl alcohol, after which serial dilutions were performed to determine the total number of viable spores in each coupon. The results showed that simulated UV-space exposed spores had a lower survivability rate than simulated dark-space exposed spores. Similarly, simulated Martian UV had a greater reduction effect on spore survivability than simulated dark Martian UV conditions. These results potentially hold strong implications for predicting the survivability of B. horneckiae communities in real space.
NASA Jet Propulsion Laboratory (JPL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).