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Evidence from recent Mars landers identified the presence of perchlorates salts at 1 wt % in regolith and their widespread distribution on the Martian surface that has been hypothesized as a critical chemical hazard for putative life forms. However, the hypersaline environment may also potentially preserve life and its biomolecules over geological timescales. The high concentration of natural perchlorates is scarcely reported on Earth. The presence of perchlorates in soil and ice has been recorded in some extreme environments including the McMurdo Dry Valleys in Antarctica, one of the best terrestrial analogues for Mars. In the frame of "Life in space" Italian astrobiology project, the polyextremophilic black fungus Cryomyces antarcticus, a eukaryotic test organism isolated from the Antarctic cryptoendolithic communities, has been tested for its resistance, when grown on different hypersaline substrata. In addition, C. antarcticus was grown on Martian relevant perchlorate medium (0.4 wt% of Mg(ClO4)2 and 0.6 wt% of Ca(ClO4)2) to investigate the possibility for the fungus to survive in Martian environment. Here, the results indicate a good survivability and metabolic activity recovery of the black fungus when grown on four Martian relevant perchlorates. A low percentage of damaged cellular membranes have been found, confirming the ultrastructural investigation. [ABSTRACT FROM AUTHOR]

One of the main objectives of astrobiological research is the investigation of the habitability of other planetary bodies. Since space exploration missions are expensive and require long-term organization, the preliminary study of terrestrial environments is an essential step to prepare and support exploration missions. The Earth hosts a multitude of extreme environments whose characteristics resemble celestial bodies in our Solar System. In these environments, the physico-chemical properties partly match extraterrestrial environments and could clarify limits and adaptation mechanisms of life, the mineralogical or geochemical context, and support and interpret data sent back from planetary bodies. One of the best terrestrial analogues is Antarctica, whose conditions lie on the edge of habitability. It is characterized by a cold and dry climate (Onofri et al., Nova Hedwigia 68:175–182, 1999), low water availability, strong katabatic winds, salt concentration, desiccation, and high radiation. Thanks to the harsh conditions like those in other celestial bodies, Antarctica offers good terrestrial analogues for celestial body (Mars or icy moons; Léveillé, CR Palevol 8:637–648, https://doi.org/10.1016/j.crpv.2009.03.005, 2009). The continent could be distinguished into several habitats, each with characteristics similar to those existing on other bodies. Here, we reported a description of each simulated parameter within the habitats, in relation to each of the simulated extraterrestrial environments. [ABSTRACT FROM AUTHOR]

Melanin is a natural pigment present in almost all biological groups, and is composed of indolic polymers and characterized by black-brown colorization. Furthermore, it is one of the pigments produced by extremophiles including those living in the Antarctic desert, and is mainly involved in their protection from high UV radiation, desiccation, salinity and oxidation. Previous studies have shown that melanized species have an increased capability to survive high level of radiation compared with the non-melanized counterpart. Understanding the molecular composition of fungal melanin could help to understand this peculiar capability. Here, we aimed to characterize the melanin pigment extracted from the Antarctic black fungus Cryomyces antarcticus, which is a good test model for radioprotection researches, by studying its chemical properties and spectral data. Our results demonstrated that, in spite of having a specific type of melanin as the majority of fungi, the fungus possesses the ability to produce both 1,8-dihydroxynaphthalene (DHN) and l 3-4 dihydroxyphenylalanine (L-DOPA) melanins, opening interesting scenarios for the protection role against radiation. Researches on fungal melanin have a huge application in different fields, including radioprotection, bioremediation, and biomedical applications. Key Points: • Isolation and characterization by multidisciplinary approaches of fungal melanins. • Discovery that pathways for producing DOPA and DHN are both active even in its extreme habitat. • Hypothesis supporting the possibility of using melanin pigment for radioprotection. [ABSTRACT FROM AUTHOR]