Paris | They had been sleeping there since the era of the dinosaurs: scientists have managed to awaken 100 million year old microbes that were buried under the ocean, in a place that was not very conducive to life, according to a study.
These results, published in the journal Nature Communications, reveal the astonishing capacities of one of the most primitive forms of life to appear on Earth, which can survive for tens of millions of years with virtually no oxygen or nutrients, and be reborn at the same time. life in a laboratory.
Ten years ago, a scientific expedition set out to drill the depths of the Pacific Ocean, and took samples of ancient sediment deposits buried 100 meters below the ocean floor (nearly 6,000 meters below the water surface) , for some for more than 100 million years.
The research team, led by the Japanese agency for underwater science and technology, had chosen the subtropical gyre of the South Pacific, the least active area of the entire ocean, because it is extremely poor in nutrients. And therefore a priori very little conducive to life.
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The researchers incubated the samples in order to help the microbes “come out” of their torpor. To their surprise, they discovered that, far from being fossilized in the sediment, the microbes had survived there, and that they were even able to grow and multiply.
“At first I was skeptical, but it turned out that 99.1% of the microbes in the 101.5 million year old sediment deposits were still alive, and ready to eat! Commented Yuki Morono, lead author of the study.
“Now we know there is no age limit for organisms in the marine subsurface biosphere,” he told AFP. “It’s a great place to explore the limits of life on Earth,” the researcher added in a statement.
It is the traces of oxygen in the sediments that would have allowed these microbes to stay alive for millions of years with virtually no energy. “Surface” microbes could not survive in such conditions.
Previous studies have shown how bacteria can live in the most inhospitable places on Earth, even without oxygen. This new research proves the remarkable persistence of these metabolisms.
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