A study reveals that recent rains in the Atacama Desert have caused the death of microbes

Life as we know it needs water to survive and thrive. But scientists have observed something unusual in one of the driest places on the planet. When the rain fell on the arid desert of Atacama, it was devastating.

The Atacama Desert, located in northern Chile, is the driest desert on Earth and only the most resistant microbes can survive there. Its hyper-arid nucleus has not received any rain in the past 500 years. When the desert finally experienced rains three years ago, it caused the extinction of most microbes that had lived there.

"Our group discovered that, contrary to what one could intuitively think, the rainfall never before seen did not unleash a flourishing of life in Atacama, but that the rains caused much of the rain. Huge devastation in the microbial species that populated the region's heavy rainfall, "said co-author Alberto Fairen of Cornell University.

"Our work shows that heavy rainfall has resulted in the massive extinction of most native microbial species. The extinction range reaches 85%, due to the osmotic stress that caused the sudden abundance of water: indigenous microorganisms, perfectly adapted to thrive in extreme drought conditions and endowed Strategies optimized for the extraction of their environment, were unable to adapt to the new conditions of sudden floods and died of excess water. "

The Atacama Desert was originally inhabited by 16 different microbial species. Only two to four species remained alive after the rain.

"The extinction event was huge," Fairen said. "Our results show for the first time that suddenly delivering large amounts of water to microorganisms – perfectly suited for extracting lean and elusive moisture from the most hyperdry environments – will kill them at once." osmotic shock. "

The results also have implications for understanding the microbiology of extremely arid environments such as Red Planet. The Atacama Desert is one of the places on Earth that presents an environment remarkably similar to that of Mars.

"Mars had a first period, the Noachian (4.5 to 3.5 billion years ago), in which there was a lot of water on its surface," Fairen said. "Our study of Atacama therefore suggests that the recurrence of liquid water on Mars could have contributed to the demise of Martian life, if it ever existed, instead of representing an opportunity for the reappearance of one. resistant microbiota. "