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Front. Microbiol. | doi: 10.3389/fmicb.2019.00069

Subsurface microbial habitats in an extreme desert Mars-analogue environment

Kimberley Warren-Rhodes1,  Stephen D. Archer2,  Kevin C. Lee2, Nathalie Cabrol1, Linda Ng-Boyle3, David Wettergreen4, Kris Zacny5 and  Stephen B. Pointing6*
  • 1SETI Institute, United States
  • 2Auckland University of Technology, New Zealand
  • 3University of Washington, United States
  • 4Carnegie Mellon University, United States
  • 5Honeybee Robotics (United States), United States
  • 6Yale-NUS College, Singapore

Sediments in the hyper-arid core of the Atacama Desert are a terrestrial analogue to Mars regolith. Understanding the distribution and drivers of microbial life in the sediment may give critical clues on how to search for biosignatures on Mars. Here, we identify the spatial distribution of highly specialised bacterial communities in previously unexplored depth horizons of subsurface sediments to a depth of 800mm. We deployed an autonomous rover in a mission-relevant Martian drilling scenario with manual sample validation. Subsurface communities were delineated by depth related to sediment moisture. Geochemical analysis indicated soluble salts and minerology that influenced water bio-availability, particularly in deeper sediments. Colonization was also patchy and uncolonized sediment was associated with indicators of extreme osmotic challenge. The study identifies linkage between biocomplexity, moisture and geochemistry in Mars-like sediments at the limit of habitability and demonstrates feasibility of the rover-mounted drill for future Mars sample recovery.

Keywords: desert soil, soil bacteria, Mars, Atacama, moisture stress

Received: 18 Jul 2018; Accepted: 15 Jan 2019.

Edited by:

Andreas Teske, University of North Carolina at Chapel Hill, United States

Reviewed by:

John R. Spear, Colorado School of Mines, United States
Gabriela Olmedo-Alvarez, Unidad Irapuato (CINVESTAV), Mexico  

Copyright: © 2019 Warren-Rhodes, Archer, Lee, Cabrol, Ng-Boyle, Wettergreen, Zacny and Pointing. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Stephen B. Pointing, Yale-NUS College, Singapore, Singapore, stephen.pointing@yale-nus.edu.sg