Pre-Historic Deep Sea Microbes Discovered in Pacific Ocean Deposits

Ancient bacteria that have not eaten for 86 million years have been found deep inside the Pacific Gyre by a team of researchers.

The microbes that have survived in marine sediments without fresh supply of organic matter for years are said to have existed well before dinosaurs were extinct. These life forms were found when the scientists were drilling into a layer of soft red clay at the bottom of the ocean.

According to a Daily Mail report, it is an area of ocean where almost nothing reaches the seabed and most plankton that die in the water dissolves long before any pieces of them can reach the seafloor far below. Only very rarely does even a single particle land in any given spot on the bottom.

The findings of the research have been reported in the latest edition of the journal, Science.

"We normally cannot see what rate they are working at. It is so slow for us, it looked like suspended animation," the New York Times quoted Hans Roy, a geomicrobiologist at Aarhus University in Denmark, saying.

Hans was reportedly part of an expedition in 2009 to sample that ancient sediment and found living bacteria buried in that clay - despite there being almost no nutrients down there for them to feed on.

In the report, the researchers calculated how much oxygen should have diffused into each layer of the sediment.

"At threshold sedimentation rates of 1 millimeter per 1000 years, the low rates of microbial community metabolism in the North Pacific Gyre allow sediments to remain oxygenated tens of meters below the sea floor," the report mentioned.

"We found that the oxygen respiration rates dropped from 10 micromoles of O2 liter-1 year-1 near the sediment-water interface to 0.001 micromoles of O2 liter-1 year-1 at 30-meter depth within 86 million-year-old sediment," it continued.

Furthermore, the researchers found that the cell-specific respiration rate decreased with depth but stabilized at around "10-3 femtomoles of O2 cell-1 day-1 10 meters below the seafloor."

This implied that the community size of the microbes found is controlled by the rate of carbon oxidation and thereby by the low available energy flux.