The Resistance of the Thermophilic Species Parageobacillus thermantarcticus in space simulated conditions

Extremophiles can be isolated from several extreme environments that resemble the environmental conditions in space and in other Solar System bodies, therefore they are considered as valuable biological models for Astrobiology studies. Indeed, thanks to their ability to survive to a variety of stressing conditions, these organisms could have been able to resist to the interstellar transport to Earth, as hypothesize by the panspermia theory of the origin of life on Earth. The relevance of extremophiles as biological models has recently been highlighted also by the "AstRoMap European Astrobiology Roadmap", that envisages the implementation of microbiological experiments in laboratory by simulating the extraterrestrial environments, in order to identify those microbial species that could potentially adapt to live in space on other planets. In this frame, we pointed out our attention on four extremophilic bacteria from the Archaea and Bacteria domains i.e. Sulfolobus solfataricus, Haloterrigena hispanica, Thermotoga neapolitana and Parageobacillus thermantarcticus. All the selected bacteria were able to resist to several stressing conditions mimicking the space environment. In particular, P.thermantarcticus showed to be one of the most resistant species after exposition to a variety of conditions from the absence of water to the irradiation with ionising radiations (x-rays and gamma-rays). In this report, our recent results regarding the adaptation and the molecular mechanisms involved in the resistance and inactivation of this species in space simulated conditions will be presented.