Hidden 'biosphere' of extreme microbes discovered 13 feet below Atacama Desert is deepest found there to date

A rich microbial "biosphere" lies buried 13 feet (4 meters) beneath the scorched surface of Chile's Atacama Desert, new research has found. The hidden world of bacteria is one of the deepest found in Atacama soils and could inform the search for life on Mars.

Microbial life has previously been recorded down to depths of 2.6 feet (80 centimeters) in the Atacama Desert, but the new biosphere, in the region's bone-dry Yungay Valley is "completely isolated from the surface," according to the researchers.

The newly discovered community inhabits soils between 6.6 feet (2 m) and at least 13 feet deep, according to a study, published Tuesday (April 23) in the journal PNAS Nexus. It is dominated by Actinobacteria, a diverse group of bacteria found in other extreme environments, including the Arctic, boiling hot springs and salty seas. 

"Little is known about microbial life in deeper sediment layers," researchers wrote in the study. "Communities described in this study could represent the upper extent of a deep biosphere underneath hyperarid desert soils."

The researchers also found Actinobacteria living closer to the surface, between 0.8 and 2 inches (2 to 5 cm) deep. Digging deeper, the team found bacteria belonging to the phylum Firmicutes, which are resilient to high concentrations of salt and do not require oxygen to survive, according to the study.

Related: Lost world of lagoons filled with mounds of microbes discovered in Atacama desert

The Atacama Desert is the driest hot desert in the world, receiving as much sunshine as Venus. While only a handful of animals survive the harsh conditions — including Darwin's leaf-eared mouse (Phyllotis darwini) and the South American gray fox (Lycalopex griseus) — some bacteria thrive in the desert's salty, mineral-rich soils.