Scientists have revived microbes found in sediments 100 million years ago from the depths of the ocean floor. The experiment sheds new light on where life can be found on Earth, and how resilient it can be.
According to a new study published in the journal Nature Communications, the microbes found buried under the seabed have persisted for up to 101.5 million years. Sediments do not have the energy required to allow cells to support themselves, but scientists were still able to revive communities.
It is a mystery how the microbes were able to survive the harsh conditions of their environment, and it is unclear how long they can live. The researchers said that they could possibly be the oldest known organisms on the planet.
Scientists from the Japan Earth and Sea Science and Technology Agency analyzed sediment samples found approximately 12,140 to 18,700 feet below the surface of the ocean in the South Pacific spin, a system of spinning currents located in the Ocean Peaceful. The center of the South Pacific turn contains the “ocean pole of inaccessibility,” the furthest point on Earth from all land, the least productive part of the entire ocean.
IODP JRSO / Nature Communications
The area has little food, but it houses a lot of oxygen under the subsoil. The sediment layers, collected during a 2010 expedition, were deposited over a period of 13 million to 101.5 million years ago.
Inside the sediment, the scientists found marine microbes – tiny, single-celled microorganisms that make up the overwhelming majority of the total mass of living creatures in the ocean. Trapped in the sediment layers, they could barely move or eat.
The researchers wanted to know if life can exist in such a nutrient-poor environment.
Back in the laboratory, the researchers were able to awaken the microbes from their long sleep. They gave the samples old substrates of carbon and nitrogen, to test if they were a power and division cable for more cells.
Over a 68-day period, the vast majority of the nearly 7,000 cells responded quickly to the new conditions, multiplying by four orders of magnitude, even in the oldest samples. The researchers said aerobic bacteria dominated the experiment.
“What we discovered is that life extends from the seafloor to the underlying rocky basement,” said oceanographer and study co-author Steven D’Hondt of the University of Rhode Island in a video news release. “Those organisms are not only alive in the deepest and oldest sediment, but they are capable of growth and division.”
“It is surprising and biologically challenging that a large fraction of microbes can be revived from a very long time of burial or entrapment under extremely low nutrient / energy conditions,” lead author Yuki Morono told Reuters.
Research indicates that microbes could survive for previously unfathomable periods of time if the sediment accumulates at a very slow rate, trapping oxygen over time.
Through more experiments, the researchers now hope to determine how the microbes could persist for millions of years.
“The most exciting part of this study is that it basically shows that there is no limit to life in the old sediment of Earth’s ocean,” D’Hondt told Reuters. “Maintaining full physiological capacity for 100 million years in starvation isolation is an impressive feat.”
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