Despite the harsh conditions, with scarce higher life forms, the hyper-arid soil rich in salts and sulfates nurtures bacteria. While the top 80 centimeters of soil offer some protection from UV light and a small amount of water, deeper layers reveal more.
Dirk Wagner and his team dug over four meters in a playa in the Yungay Valley to gather soil samples using an innovative extraction method that isolates DNA from living organisms. This process involved washing out loose DNA and extracting the DNA within intact cells for sequencing.
Analysis showed that while microbial communities in the top 80 cm of playa sediments were mainly Firmicutes, a distinct community dominated by Actinobacteria existed below 200 cm.
Genetic analysis linked some bacteria to species like Geodermatophilus pulveris and Modestobacter caceresii. The study suggests these microbes might have colonized the soil 19,000 years ago, before being covered by playa deposits, possibly extending further into the subsurface, indicating a previously unrecognized deep biosphere under hyper-arid desert soils.
The deep bacterial community may utilize gypsum as a water source, mirroring conditions that could support microbial life on Mars, given its similar gypsum deposits.
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