image: The Atacama Desert in Northern Chile with gypsum rocks in the foreground. view more
Credit: Image credit: Jocelyne DiRuggiero.
Researchers examine how Atacama Desert microbes use rocks as a water source. Several microbes in desert environments live inside rocks. To survive, such endolithic microbes rely on the ability of rocks to retain water. However, it is unclear how microbes extract water from rocks and how such mechanisms affect rocks. Using a combination of microscopy and spectroscopy, David Kisailus and colleagues examined colonized gypsum rocks collected in Chile's Atacama Desert, one of the driest places on Earth. Photosynthetic microbes living inside the rocks extracted structurally ordered water from gypsum, leading to gypsum's transformation into anhydrite. The microbes attached to high-energy crystal planes and produced a biofilm composed of organic acids. The biofilm prompted mineral dissolution and water extraction, subsequently leading to the rock's phase transformation. X-ray diffraction showed that the dehydrated anhydrite rock existed only where microbes were populated. The authors also grew an isolated strain of cyanobacterium on gypsum samples in either the presence or absence of water during a 30-day incubation period, after which they found that only colonized gypsum with no water had transformed to anhydrite. The findings suggest that endolithic microbes have adapted to extremely dry environments, according to the authors.
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Article #20-01613: "Mechanism of water extraction from gypsum rock by desert colonizing microorganisms," by Wei Huang et al.
MEDIA CONTACT: David Kisailus, University of California, Irvine, CA; tel: 805-403-2903; email: david.k@uci.edu
Journal
Proceedings of the National Academy of Sciences