A research team from the Japan Earth and Sea Science and Technology Agency (JAMSTEC) and the Graduate School of Oceanography at the University of Rhode Island have collected samples of microbes from the seafloor up to 100 million years old that have been revived, and multiplied, under laboratory conditions.
The samples were obtained on an expedition to the South Pacific Gyre, as published in Nature Communications.
From the time of the dinosaurs
On board the JOIDES Resolution research vessel, the team drilled numerous sediment cores 100 meters below the seabed and almost 6,000 meters below the ocean surface.
At the bottom of the sea, there are layers of sediment consisting of marine snow (organic debris continually coming from the sea surface), dust and particles carried by wind and ocean currents. Small life forms like microbes get caught in this sediment. As explained by the main author of the cited study, Yuki Morono, chief scientist at JAMSTEC:
Our main question was whether life could exist in an environment with such nutrient limitation or whether it was a lifeless area. And we wanted to know how long microbes could sustain their lives in an absence of food.
The results showed that, instead of being fossilized remains of life, microbes in the sediment they had survived and were able to grow and divide.
At first I was skeptical, but we found that up to 99.1% of the microbes in sediment deposited 101.5 million years ago were still alive and ready to eat.
The most remarkable thing about this study is that it shows that there are no limits to life in the old ocean sediment, so a similar approach could be applied to other questions about the geological past. Definitely, the subsoil is an excellent location to explore the limits of life on Earth.
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