Japanese researchers say they have confirmed the existence of a community of micro-organisms thriving in a seabed layer formed more than 400,000 years ago in northern Japan.
The team of researchers from the Japan Agency for Marine-Earth Science and Technology's Kochi Institute for Core Sample Research and the University of Tokyo dug up the micro-organisms from the seafloor at a depth of 1,180 meters and about 80 kilometers off Hachinohe, Aomori Prefecture.
Yuki Morono, a senior microbiologist at the institute who led the team, retrieved a sample of the micro-organisms from a layer 219 meters under the seabed. That stratum was estimated to have been formed 460,000 years ago.
Using a high-performing mass spectrometer, the researchers observed if nutrient sources, such as glucose and pyruvic acid, containing marked carbon and nitrogen, were being absorbed by the micro-organisms.
Two months after the researchers began cultivating the creatures with nutrients, they confirmed that more than 10 million micro-organisms per 1 cubic centimeter were taking in the nutrient sources.
The microbiologists said this proves the existence of a community of micro-organisms below the seafloor, although they have yet to determine what species those minute creatures are.
The research was conducted using the deep sea drilling vessel Chikyu.
The micro-organisms were absorbing nutrient sources at a speed 1/100,000th that of E. coli bacteria. At this rate, it is possible for the creatures to survive under the seabed despite the scarcity of nutrients, they said.
Reserves of methane hydrate, a possible energy source, exist near the 460,000-year-old stratum.
"We want to uncover the role that micro-organisms play in the creation of energy sources," Morono said.
The findings were carried last month in the online edition of the Proceeding of the National Academy of Sciences of the United States of America.
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