POTSDAM, Germany —
One of the most intriguing discoveries in recent times has been made deep beneath Chile’s Atacama Desert. In a place that was once considered one of the most lifeless on Earth, scientists have uncovered a hidden underground biosphere teeming with microscopic life. This remarkable find is challenging our understanding of life on our own planet and potentially providing insights into the possibility of life existing under the barren surfaces of other celestial bodies, such as Mars.
Despite being known as the driest desert on Earth, with some areas experiencing decades or even centuries without rainfall, a team of German researchers from the GFZ German Research Centre for Geosciences has stumbled upon communities of resilient microorganisms that have managed to thrive in the deep recesses of the desert floor. Isolated from the surface world, these microscopic organisms have defied all odds and adapted to survive in extreme subterranean environments.
Lead study author Dirk Wagner and his team detected signs of potentially viable microbial ecosystems as deep as 13 feet underground. This groundbreaking discovery challenges our understanding of desert biodiversity, indicating that life can endure in even the harshest underground conditions on Earth.
To unveil this hidden world, the researchers developed an innovative DNA extraction technique to retrieve genetic material exclusively from cells containing intact membranes – a reliable indicator of living or dormant organisms. Traditional methods often capture remnants of dead cells, which obscure the true nature of the environment being studied.
The findings, published in the journal PNAS Nexus, unveil two distinct microbial communities inhabiting different subsurface layers. Near the surface, salt-loving bacteria battle for survival in highly saline sediments once connected to an ancient ephemeral lake or playa. Surprisingly, deeper below the surface, older alluvial fan deposits host a resurgence of life, with microbial communities potentially colonizing these lower layers more than three million years ago. Over time, they became isolated and cut off from the world above, leading them to develop astonishing strategies for survival in such extreme isolation.
One crucial aspect sustaining this underground oasis is the presence of certain mineral deposits, particularly gypsum crystals. These crystals undergo a chemical transformation into anhydrite, allowing certain microbial species to extract and metabolize trapped water molecules. Slowly, these organisms can sustain themselves with enough moisture to survive.
What is even more astounding is that many of the identified microbes rely on an obscure type of chemosynthetic metabolism. Unlike most life forms on Earth, they gather sustenance from atmospheric gases like carbon dioxide and hydrogen, rather than relying on sunlight or organic matter from surface ecosystems.
The significance of this discovery extends beyond the Atacama Desert and challenges our perception of desert ecosystems, including those on other planets. Billions of years ago, Mars may have hosted environmental conditions similar to those in the Atacama. This revelation sparks speculation that subsurface refuges holding dormant or even active microbial life may exist on Mars, awaiting human exploration.
