Radiation resistance of the extremophiles: Implications for astrobiology

The extremophiles are microorganisms able to thrive in extreme environmental conditions and include bacterial species belonging to both Bacteria and Archaea domains of life. The ability to resist several harsh chemical and physical conditions make them of great interest for astrobiology, i.e., the multidisciplinary approach to the study of the origin and evolution of life on Earth and in the universe. The resistance to radiations like ultraviolet radiations or ionizing radiations, the main components of the cosmic rays, is one of the main issues in astrobiology in relation to the search for bacterial species that, according to the panspermia theory, could adapt to life in space or that could have survived the interstellar transport. Here we present an overview of recent researches concerning the ability of extremophilic bacteria to resist solar and ionizing radiations. The relevance for the study of adaptability of terrestrial life forms in space environments or exoplanets, is also discussed