Search of life in a Mars analogue site ‐ microbes and associated biosignatures in the deep and completely dark salt caves of the Atacama Desert

Abstract

Salt caves are scarce and poorly investigated mainly because they only exist in extremely remote and arid regions, such as the Atacama Desert (Chile). The Cordillera de la Sal (San Pedro de Atacama) is one of the most important rock salt karst areas in the world forming a Mars‐like landscape. The detection of microorganisms and biosignatures preserved in halite speleothems from these hypersaline cave systems is of particular interest for understanding the limits of microbial life, the origin of life on Earth, and predict extraterrestrial habitability. State‐of‐the‐art techniques were used for the accurate characterization of microbial cells and organic molecules from halite speleothems collected in Cueva Cressi. This study involved a multi‐proxy approach, including metagenomics, FESEM‐EDS, Py‐GC/MS and stable isotopes (EA‐IRMS). We identified and isolated halophilic microorganisms, such as Salinisphaera sp. and Haloparvum sp., and were able to detect lipid compounds in the speleothems. In this communication, we will present the first data on this fascinating Mars‐like ecosystem and introduce novel techniques for the detection of biosignatures and the direct determination of the isotopic composition of environmental samples from extreme and Mars analogue field sites.