Microbes Found in 86 Million-Year-Old Clay Deep Beneath the Ocean

Posted on May 18, 2012

Researchers have found bacteria inside 86 million-year-old clay deep beneath the seafloor of the North Pacific Gyre. The bacteria are surviving on tiny amounts of nutrients and oxygen that has been trapped in the clay since the days of the dinosaurs. The bacteria down there breathe 10,000 times as slow as a common E.coli bacterium. They require extremely little energy to live.

Because these microbes live life in such slow-motion, scientists would have to wait a thousand years before noticing any change in the deep-sea microbes. However, the scientists were able to determine that the bacteria living in these sediments are alive and actively using up oxygen (albeit extremely slowly) by using needle-shaped oxygen-sensors.

The microbes turn over their sediment biomass at a rate of once every few hundred years to once every few thousand years. This may reflect cell division, but could also simply indicate a one thousand year cell repair cycle. At the bare minimum, microbes need energy to maintain an electric potential across their membrane and to keep their enzymes and DNA working, and Roy and colleagues suspect these microbial communities may be living at the minimum energy requirement needed to subsist, but they don't have any specific evidence yet.

The scientists, led by Hans Roy at Aarhus University in Aarhus, Denmar, say, "it's clear that this microbial community --which has not received food from the outside world since the dinosaurs walked the earth -- is still alive and active."

Roy told the L.A. Times, "What they're doing, they're doing so slow that from our time perspective, it just looks like suspended animation."

Roy also told National Geographic that these microbes are "still eating the same lunch box" as when the dinosaurs walked the Earth. He also says the DNA of the microbes does not match that of any other known bacteria species.

The scientists also say their study suggests that all the knowledge scientists have accumulated about fast-growing laboratory microorganisms probably doesn't apply to slow life beneath the ocean. Microbes make up 90% of the ocean's total biomass, but we still don't know much about them. National Geographic has an interesting gallery of some of these marine microbes here.

The study of the deep-sea microbes was published here in the journal, Science.