In the northern Pacific Ocean, buried 20 meters below the ocean floor, are bacteria that live life in the extreme slow lane. They have not received any fresh sources of food since they were buried 86 million years ago, when dinosaurs still walked the land. Still, they cling to life by using up the little oxygen available to them at an incredibly slow rate.
“Their activity is so slow that on our timescale, nothing happens at all,” said Hans Røy from Aarhus University, who discovered the microbes. “It’s much less than any laboratory culture we have.”
“Besides being interesting on its own, it has large implication for the potential of life in other low energy environments such as the subsurface of Mars,” added Arthur Spivack from the University of Rhode Island, who was not involved in the study.
The study, published today (May 17) in Science, is part of Røy’s ongoing effort to understand the organisms that live in marine sediments, which could account for 90 percent of all microbes in the world. “We’re looking at the most common forms of life on this planet, and we know almost nothing about them,” said Røy.
Extremely slow-going bacteria were discovered in the surface of the ocean floor in the 1990s, but many scientists initially dismissed them as dead. A Japanese group challenged that idea last year, when they showed that cells buried in sediments from the Sea of Japan could grow if they were given a fresh source of nutrients. Now, Røy has gone one step further by measuring the metabolism of subsurface bacteria in their native soil, and confirming that they are alive, if barely so.
The team collected the buried microbes on a research cruise that sailed west along the Equator from the Galapagos Islands, before turning north into a rotating collection of currents called the North Pacific Gyre. At nine stops along the way, the researchers drilled into the ocean floor to collect cylinders of sediment, 28 meters deep.