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Millennia-Old Microbes Found Alive in Deep-Ocean Muck

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mud-coreA sparse community of microbes can persist for eons in the clay beneath the deep blue sea. When scientists drilled into the Pacific Ocean bottom and pulled up a long core of clay, they also pulled up microbes living on so little that it was hard for the scientists to tell if they were alive in the first place.

The microbes are still being precisely identified but they are not like the other deep-sea extremophiles that scientists have found everywhere from hydrothermal vents to more than a kilometer beneath some parts of the ocean floor. These microbes, like those closer to the surface, rely on oxygen to live—unlike other denizens of the deep sea muck that find the reactive element inimical to their lifestyle and were driven to the dark, secret places of the planet when photosynthetic organisms like plankton began to fill the atmosphere with oxygen more than 2 billion years ago.

The site where these microbes were found is beneath the North Pacific Gyre, a massive whirl of current north of Hawaii. Since there is hardly any land nearby, precious little dead plankton and other nutritious detritus falls to the seafloor—only 0.2 millimeters accumulates every thousand years—and what does mostly gets consumed by quicker-living microbes on the surface of the seafloor. But when scientists drilled a core during a cruise of the Woods Hole Oceanographic Institution’s Knorr research vessel, they found roughly 1,000 cells of these bacteria and archaea living in extreme slow-motion per cubic centimeter’s worth of mud core from 20 meters below the bottom of the ocean.

That depth suggests these microbes have persisted for 86 million years and haven’t seen fresh food since dinosaurs roamed the Earth. To cope, these newly-found microbes use oxygen to respire—or convert food into energy and release the waste byproducts—10,000 times slower than microbes on the surface of the seafloor, leading the scientists who conducted the research, and published it in Science on May 18, to write that “these microbial communities may be living at the minimum energy flux needed for prokaryotic cells to subsist.”

That also suggests that these microbes might be thousands of years old—or even older—thanks to an extreme lifestyle of eating, breathing and building new cells only every few hundred years or more. In other words, live slow to die old.

Image: Photo by Bo Barker Jørgensen © Science / AAAS

About the Author: David Biello is the associate editor for environment and energy at Scientific American. Follow on Twitter @dbiello.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. jtdwyer 11:02 pm 05/18/2012

    Good report – I don’t have access to the research report but others news reports do not even mention that “they found roughly 1,000 cells of these bacteria and archaea living in extreme slow-motion per cubic centimeter’s worth of mud core…”

    They do infer that these microbes must have been originally buried in seafloor level clay, which became increasingly anaerobic as the strata accumulated. However, that would require that the microbes living near the ocean floor were capable of adopting some state of ‘hibernation’ to allow them to persist for these many millions of years since their burial.

    Has it been definitively determined that these microbes are not species that are specially adapted to the extreme conditions in which they’re found?

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  2. 2. singing flea 4:11 am 05/19/2012

    It makes one wonder what other kinds of life can be re-introduced into the modern world with this type of exploration. Is it possible that some long since buried virus or bacteria that could potentially kill humans be re-established as a new pandemic?

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  3. 3. geojellyroll 9:55 am 05/19/2012

    singing flea….no, there is nothing to fear from a bacteria that did not evolve to live in some relationship with multi-celled animals. We encounter thousands of new species (hundreds of billions in numbers) of bactera every day.

    Really interesting stuff. I’m sure everyone involved in biology regimens first thought about the equivalent of ‘quality control’ in these observations.

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  4. 4. Dragonkill460 1:16 pm 05/19/2012

    is there any proof to how old you say these things are? carbon dating is not quite 100% effective and the microbes are too small to be carbon dated anyway. how do you know that these things are millions of years old? what if they are like alligators or sharks that have survived since dinosaur times who reproduce and have a life span of about 20 years?

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  5. 5. singing flea 8:05 pm 05/19/2012

    Jellyroll says,”…no, there is nothing to fear from a bacteria that did not evolve to live in some relationship with multi-celled animals.”

    I am not worried about did not “evolve to live in some relationship with multi-celled animals.” I am concerned about the ones that did.

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  6. 6. jb1964 12:31 pm 05/20/2012

    I would imagine that over the course of millions of years, the DNA of these microbes would be severely compromised. I can’t imagine how they could still be living. Yes, there are DNA repair mechanism, but if the metabolism is 10,000x slower than normal, the rate of damage vs the rate of repair is skewed in favor of damage.

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