A team of scientists from the United States and Japan were looking to see if microscopic organisms could survive in the less-than-hospitable conditions beneath the seafloor of the Pacific Ocean, reports Science Alert.
“We wanted to know how long the microbes could sustain their life in a near-absence of food,” said microbiologist Yuki Morono from the Japan Agency for Marine-Earth Science and Technology, who led the study.
The team’s research, published in the journal Nature Communications on July 28, found that microbes trapped in seabed sediments deposited 100 million years ago could be revived with the right food and a bit of added oxygen.
The list of microbes found in the subfloor sediment spans 10 major and minor groups of bacteria, including spore-formers, although they were only a minor constituent of the microbial communities. The microbes may be the planet’s oldest-known organisms, reports CBC Canada.
According to the scientists, the microbes were present in clay samples drilled from the research vessel JOIDES Resolution about 74.5 meters (243 feet) under the sea floor, below 5.7 kilometers (3.7 miles) of water. About 99 percent of the microbes found date back to the age of the dinosaurs.
The soil samples were taken from a 2010 expedition to the South Pacific Gyre, a seemingly lifeless zone in the center of swirling ocean currents to the east of Australia, one of the most food-limited and life-deficient parts of the ocean.
“We knew that there was life in deep sediment near the continents where there’s a lot of buried organic matter,” said Morono’s colleague, geomicrobiologist Steven D’Hondt from the University of Rhode Island. “But what we found was that life extends in the deep ocean from the seafloor all the way to the underlying rocky basement.”
Once onboard the ship, the microbes were given a boost of oxygen and fed traceable substrates containing carbon and nitrogen, their food of choice, before the glass vials were sealed, incubated and only opened after 21 days, 6 weeks or 18 months. The microbes grew, multiplied and displayed diverse metabolic activities, according to Reuters.
“The most exciting part of this study is that it basically shows that there is no limit to life in the old sediments of Earth’s oceans,” said University of Rhode Island oceanographer Steven D’Hondt, co-author of the study. “Maintaining full physiological capability for 100 million years in starving isolation is an impressive feat,” D’Hondt added.
