In a discovery with implications for the search for extraterrestrial life, microbial life has been discovered almost four meters under the Atacama Desert, the most inhospitable in the world.
Although higher life forms are almost entirely absent, the hyperarid soil, rich in salts and sulfates, harbors bacteria. The top 80 centimeters of soil are thought to be a possible refuge from the intense ultraviolet light, a place where some water could be found.
Dirk Wagner of the Institute of Geosciences at the University of Potsdam and his colleagues sought to extend the understanding of desert biota to the deep subsurface world. The authors dug more than four meters deep on a ‘beach’ in the Yungay Valley to collect soil samples.
They devised a new extraction method to ensure that the DNA sampled came from living organisms. Loose DNA was first washed and then DNA was extracted from inside the intact cells for sequencing. The findings are published in PNAS Nexus.
In the upper 80 cm of the sediments, microbial communities were dominated by Firmicutes. Below 200 cm, a different microbial community was discovered, dominated by actinobacteria. Some bacteria showed genetic similarity with Geodermatophilus pulveris and Modestobacter caceresii.
The authors suggest that this community could have colonized the soil 19,000 years ago, before being buried by sand deposits, and hypothesize that the community could continue downward for an indefinite distance, representing a previously unknown deep biosphere beneath desert soils. hyperarid.
The deep bacterial community possibly depends on the gypsum for water. The authors note that Mars also has gypsum deposits, which could theoretically serve as a water source for microbial life.
