Chile: 19,000-year-old biosphere with links to Mars discovered beneath desert floor

Amazing stuff!

"...

Gene sequencing revealed an abundance of diverse microbial communities across the different layers.

Most of the sequences were assigned to bacteria; 0.5% were archaea, single-celled microorganisms similar in structure to bacteria but evolutionarily distinct. Archaea are thought to constitute an ancient group between bacteria and eukaryotes or organisms whose DNA-containing cells contain a distinct nucleus. Three bacterial groups (phyla) dominated, accounting for over 90% of genetic sequences: Actinobacteria, Firmicutes, and Proteobacteria. ...
Ecologically speaking, the playa deposits are relatively young; sedimentation started about 19,000 years ago. However, the alluvial deposits are much older, with depths of 4.2 m dating back up to 3.8 million years. ..."

"Summary For a long time, the extremely dry soils of the Chilean Atacama Desert were considered completely lifeless. In one of its driest regions, a team of scientists ... from the GFZ German Research Centre for Geosciences, together with colleagues from the TU Berlin and the University of Antofagasta, Chile, has now uncovered a previously unexplored underground habitat. This was based on newly developed methods of molecular DNA analysis, which allow the focussed extraction and analysis of intracellular DNA. This comes from intact cells of living or dormant organisms, making it possible to detect viable and potentially active microbial communities which inhabit hyperarid soils down to a depth of 4.20 metres. The study, published in the journal PNAS Nexus, thus expands our understanding of biodiversity of a region where extreme conditions of drought, salinity and nutrient deficiency are close to the limits of life. The results also have implications for the search for life on other planets."

From the abstract:

"Desert environments constitute one of the largest and yet most fragile ecosystems on Earth. Under the absence of regular precipitation, microorganisms are the main ecological component mediating nutrient fluxes by using soil components, like minerals and salts, and atmospheric gases as a source for energy and water. While most of the previous studies on microbial ecology of desert environments have focused on surface environments, little is known about microbial life in deeper sediment layers. Our study is extending the limited knowledge about microbial communities within the deeper subsurface of the hyperarid core of the Atacama Desert. By employing intracellular DNA extraction and subsequent 16S rRNA sequencing of samples collected from a soil pit in the Yungay region of the Atacama Desert, we unveiled a potentially viable microbial subsurface community residing at depths down to 4.20 m. In the upper 80 cm of the playa sediments, microbial communities were dominated by Firmicutes taxa showing a depth-related decrease in biomass correlating with increasing amounts of soluble salts. High salt concentrations are possibly causing microbial colonization to cease in the lower part of the playa sediments between 80 and 200 cm depth. In the underlying alluvial fan deposits, microbial communities reemerge, possibly due to gypsum providing an alternative water source. The discovery of this deeper subsurface community is reshaping our understanding of desert soils, emphasizing the need to consider subsurface environments in future explorations of arid ecosystems."

19,000-year-old biosphere with links to Mars discovered beneath desert Abundant, diverse bacterial communities have been found deep beneath the almost uninhabitable surface of the Atacama Desert in Chile. The researchers who discovered them say they're likely 19,000 years old and could be linked to microbial life on Mars.

Newly discovered microbial communities beneath the Atacama Desert (original news release)

Hidden biosphere beneath world’s driest hot desert

Persistent microbial communities in hyperarid subsurface habitats of the Atacama Desert: Insights from intracellular DNA analysis (open access)

Abundant, diverse microbial communities live deep under the surface of the hyper-arid Atacama Desert

The microbial composition of different subsurface depths