Scientists have brought back to life microbes found in sediments about 100 million years ago from the ocean floor. The experiment sheds new light on where life on Earth can be found, and how resilient it can be.
According to a new study published in the journal Nature Communications, microbes found buried under the sea have persisted for up to 101.5 million years. Sediments do not have the energy to allow cells to survive, but scientists were able to revive communities.
It is a mystery how microbes were able to survive the harsh conditions of their environment and it is not clear how long they can live. The researchers said they could possibly be the oldest organisms on the planet.
Scientists from the Japan Navy’s Earth Science and Technology Agency analyzed sediment samples found approximately 1800 to 18,700 feet below the surface of the South Pacific Ocean Gyre, a system of rotating currents located in the Pacific Ocean. The center of the South Pacific Gyre contains the “ocean pole of inaccessibility,” the Earth’s farthest place from all the earth, the least productive part of the entire ocean.
The area has little food, but harbors a lot of oxygen under the ground. The sediment layers, collected during a 2010 expedition, were deposited over a period of 13 to 101.5 million years ago.
In the sediment, scientists found marine microbes: tiny single-celled microorganisms that make up the overwhelming majority of the total mass of living ocean creatures. Trapped in the sediment layers, they could barely move or eat.
The researchers wanted to know if life can exist in such a nutrient-deficient environment.
In the lab, researchers were able to extract the microbes from their long sleep. They gave the old samples carbon and nitrogen substrates, to test if they were power cords and they split into 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’ve found is that life flows from the entire sea to the underlying rocky basement,” University of Rhode Island oceanographic videographer and co-author of the study Steven D’Hondt said in a press release. “These organisms are not only alive in the deepest, oldest sediments, but they are able to grow and divide.”
“It’s amazing and biologically challenging that a large portion of microbes could be revived long from burial or trapping in extremely low energy / energy conditions,” lead author Yuki Morono told Reuters.
Research indicates that microbes could survive for previously unfathomable periods of time if sediment builds up at a very slow rate, trapping oxygen over time.
Through other experiments, researchers now hope to determine how microbes may have persisted 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 by isolating yourself from hunger is an impressive feat.”