Biogeosciences, 9, 2275-2286, 2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
26 Jun 2012
Novel water source for endolithic life in the hyperarid core of the Atacama Desert
J. Wierzchos1, A. F. Davila2, I. M. Sánchez-Almazo3, M. Hajnos4, R. Swieboda5, and C. Ascaso1 1Museo Nacional de Ciencias Naturales, MNCN-CSIC, Madrid, Spain
2NASA Ames Research Center, Moffett Field, USA
3Universidad de Granada CIC, Granada, Spain
4Institute of Agrophysics PAN, Lublin, Poland
5Medical University of Lublin, Lublin, Poland
Abstract. The hyperarid core of the Atacama Desert, Chile, is possibly the driest and most life-limited place on Earth, yet endolithic microorganisms thrive inside halite pinnacles that are part of ancient salt flats. The existence of this microbial community in an environment that excludes any other life forms suggests biological adaptation to high salinity and desiccation stress, and indicates an alternative source of water for life other than rainfall, fog or dew. Here, we show that halite endoliths obtain liquid water through spontaneous capillary condensation at relative humidity (RH) much lower than the deliquescence RH of NaCl. We describe how this condensation could occur inside nano-pores smaller than 100 nm, in a newly characterized halite phase that is intimately associated with the endolithic aggregates. This nano-porous phase helps retain liquid water for long periods of time by preventing its evaporation even in conditions of utmost dryness. Our results explain how life has colonized and adapted to one of the most extreme environments on our planet, expanding the water activity envelope for life on Earth, and broadening the spectrum of possible habitats for life beyond our planet.

Citation: Wierzchos, J., Davila, A. F., Sánchez-Almazo, I. M., Hajnos, M., Swieboda, R., and Ascaso, C.: Novel water source for endolithic life in the hyperarid core of the Atacama Desert, Biogeosciences, 9, 2275-2286,, 2012.
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