(ORDO NEWS) — Researchers have successfully restored microbes that have been in a state of suspended animation in the lifeless zone of the seabed for over 100 million years.
A team of scientists from Japan and America searched for microscopic life in less than hospitable conditions under the seabed of the Pacific Ocean.
“We wanted to know how long microbes can sustain their lives in an almost complete lack of food,” said microbiologist Yuki Morono of the Japan Agency for Science and Technology.
They got the answer: microbes that were trapped in sediments deposited 100 million years ago can be restored with the right nutrient medium and a little added oxygen.
When life is trapped in other high-pressure environments, fossils are usually formed over a million years or more, but these microbes were in a state of suspended animation.
“We knew there was life in deep sediments near continents where there is a lot of buried organic matter,” said Morono’s colleague, geomicrobiologist Stephen D’Hondt of the University of Rhode Island. “But we found that life stretches in the deep ocean from the seabed to the very rocky foundation.”
As part of the expedition aboard the drilling ship Resolution JOIDES, the team recovered sediment cores extending 75 meters below the seabed, which is nearly 6 kilometers below the ocean’s surface.
They took samples from ancient pelagic clay that accumulates in the deepest and most remote parts of the ocean, and much younger than the Cretaceous nannofossil silts, which are between 4.3 and 13 million years old.
They found oxygen-scavenging microbes (and dissolved oxygen) in every layer of the core, from top to bottom, and in every site the scientists sampled.
On board the ship, sediment core samples were taken to see if the microbes lacking energy retained their “metabolic potential” and could feed and reproduce.
Ancient microbes were given a charge of oxygen and fed on substrates containing carbon and nitrogen. Even in the oldest sediment samples, the researchers were able to restore up to 99 percent of the original microbial community.
After a long incubation, microbial communities were sorted by genes. The researchers reported that bacteria predominate in the soils of the seabed, but not the type that forms spores, which means they were ready to grow as soon as they were given the right food.
The microbes quadrupled their population and consumed carbon and nitrogen 68 days after incubation.
“This shows that there are no limits to life in the old sediment of the world’s oceans,” D’Hondt said. “The oldest sediment we drilled, with the least food, still has living organisms, and they can wake up, grow and multiply.”
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