Abstract EANA2024-47

In recent years, astrobiology has made extraordinary progress; a lot of scientists have moved their research on defining the limit of life on our planet and the search for life in outer space [1]. In this context, the project CRYPTOMARS aims to outline the characteristics of a possible microbial community that could potentially have lived on Mars using terrestrial analogues. In particular, the ice-free areas of Antarctica, such as the McMurdo Dry Valleys, constitute some of the oldest, coldest, driest, and most oligotrophic areas on Earth [2]; there, environmental parameters are very similar to the ones described on Mars [3], which is why these regions are accounted as one of the best “Martian analogues on earth” [1] and life is not possible except for specialized microbial species colonizing the interstices of porous rocks, adopting cryptoendolithism as a survival strategy [4]. Antarctic cryptoendolithic communities can be, thus, considered as a proxy to evaluate and understand  if and how microbial species may have lived on Mars or Mars-like planets. These communities may have potentially adopted survival strategies similar to the one adopted by Antarctic cryptoendolithic assemblages before their extinction [5]. Recent studies conducted in the Victoria Land in Continental Antarctica allowed a detailed screening of taxonomic, metabolic and functional diversity of antarctic cryptoendolithic communities, by using next generation sequencing (NGS) techniques [6]. Based on these available data, we are actually conducting pilot experiments for the CRYPTOMARS project with the aim to optimize on colonized rock samples several viability and metabolic activity assays (e.g.  the PMA (Propidium monoazide), the Fluorescein Diacetate, the MTT and the ATP assays.).  The very first step is to set a selection of colonized rocks samples, then reactivated by rehydration and incubation at 15°C for 96 hours. Samples are exposed to selected stresses, similar to the ones they will be subjected for CRYPTOMARS. After that, vitality is tested with colorimetric analysis, by detection of active metabolism through, for example, Fluorescein diacetate, Thiazolyl blue tetrazolium bromide assay (MTT), and ATP assay. To complete the analysis, samples get seeded in plates with MEA (Malt Extract Agar) and PCA (Plate Count Agar) to detect growth of fungi, algae and bacteria. Where applicable, vitality is also verified with molecular approach by propidium monoazide assay (PMA) which binds the DNA of the damaged cells preventing the amplification, allowing the viable cells one only. The results on vitality tests will give a clear picture of the survival capability of each community under specific stress before proceeding with the whole experiments.

 

References:

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[5] Selbmann,L.; De Hoog, G.; Mazzaglia, A.; Friedmann, E.; Onofri, S. Fungi at the edge of life: Cryptoendolithic black fungi from Antarctic desert. Stud. Mycol. 2005, 51, 1–32.

[6] Claudia Coleine et al.; Antarctic Cryptoendolithic Fungal Communities Are Highly Adapted and Dominated by Lecanoromycetes and Dothideomycetes, 2018.