The driest desert on Earth: Microbes found in the Atacama Desert, Chile.

A new study has confirmed that a cold-resistant bacterial community could survive for 10 years in Chile's Atacama Desert, the driest and most uninhabitable environment on Earth, without water.
this work should allay many people's doubts, since much of the previous evidence of the presence of microbes in this remote region has come from transient microbes.
, because the soil in this place is very similar to the soil on Mars, these desert ers may offer hope to scientists searching for life on the equally hostile surface of the red planet.
the study was "a good example of how these creatures do live there."
Julie Neilson, an environmental microbiologist at the University of Arizona in Tucson who was not involved in the study, said.
the Atacama Desert may be uninhabitable for us, but for these creatures, "it's their ecosystem."
said.
the Atacama Desert extends 1,000 kilometres inland from Chile's Pacific coast, with less than 8 mm of rainfall per year.
there was little precipitation and little weathering, so over time the surface formed a hard layer of salt that further inhibited life activity there. "You can drive 100km without seeing anything like a grass leaf," says
Neilson.
"Although she and others found some bacteria there, many biologists believe that these microbes are not full-time residents, but are blown by the wind, where they die slowly."
that didn't stop Dirk Schulze-Makuch, a astrobiologist at the Technical University of Berlin in Germany.
", "I like to go to places where people say nothing."
," he said, "we decided to take a bird's gun approach and use all the new analytical methods for everything that might be there - fungi, bacteria, viruses."
" Schulze-Makuch and his team collected samples from the Atacama Desert at eight locations from the coast to the east to the driest place over three years.
they collected material for the first time after record rainfall in 2015, and then collected samples in some places in 2016 and 2017.
researchers sequenced a known gene that distinguishes microbial species to determine which microbes exist in these samples, and even some complete genomes can be found.
researchers also conducted a test to determine the proportion of DNA extracted from complete living cells.
finally, they assessed the amount of cell activity, the number of adenosine triphosphate (ATP, a molecule that fuels this activity), and the number of by-products (including fatty acids and protein modules) that are caused by these activities.
these are additional evidence of life.
Schulze-Makuch and colleagues report in the February 26 issue of the Proceedings of the National Academy of Sciences that coastal samples contain the largest number of microorganisms and are most diverse.
but in 2015, there were signs of life even in the driest places. "After the rainfall events, there was a lot of life activity and cell replication," said
Neilson.
" the researchers point out that, in general, coastal areas are the most life-friendly during the rainy season and dry years.
generally speaking, the number of ATP is 1,000 times that of the inland region, and the number of decomposition products follows a similar trend.
these genomes also suggest that at least some bacteria can reproduce in coastal areas or elsewhere.
Over the next two years, most of these areas were arid, and those numbers declined everywhere, especially in the driest.
by 2017, signs of life in most places will almost disappear, and in the driest places, the amount of intact DNA will be only one in 100,000 of the normal.
but Schulze-Makuch points out that some bacteria continue to thrive 25 cm underground.
in their study, the researchers identified only bacteria whose DNA was similar to that in the microbial database.
so the bacteria they found in the Atacama Desert are somewhat familiar.
in wet years, bacteria in coastal areas are similar to typical sandy soil microbiomes.
DNA from dry areas is mainly bacteria found in very dry deserts or salt marshes.
they are likely to survive, like spores or cells that are barely living.
the creatures may hibernate indefinitely, leading Neilson and Schulze-Makuch to speculate that some creatures could do the same thing on Mars, perhaps in the evening snowfall.
, Schulze-Makuch said, the Atacama Desert "can serve as a model for Mars."
The Atacama Desert is a desert region in the middle of the west coast of South America, stretching about 1,000 km north and south between the Andes and the Pacific Ocean, with a total area of about 181,300 square kilometres, with the main body located in Chile and partly in Peru, Bolivia and Argentina.
under the combined influence of subtropical high-pressure belt subsidence, offshore wind and Peruvian cold current, the Atacama Desert is one of the driest regions in the world, known as the world's "dry pole", and has a distinct unique characteristic sharply in the tropical arid climate type on the west coast of the mainland, forming a long, long-term coastal, vertical lyve desert belt.
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