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This expedition aims to clarify deep underground biological activity that is believed to play an important role in the system of carbon cycling below the sea floor. Along with collecting physical data on the formations at the sea area offshore of Hachinohe , core samples were collected from 1,276.5 m to 2,466 m below the sea floor.

We will carry out cutting-edge research merging earth and life sciences to assess the activity of underground microorganisms involved in producing methane hydrates and natural gas originating in coal beds under the deep sea floor. This will include analyzing microbial DNA and microbial culture experiments to investigate their metabolic function and evolutionary processes.

Detailed research results from this expedition will be published in international journals.

The expedition team established a new record in the world's history of scientific ocean drilling on September 6, 2012, when they drilled beyond 2,111 m below the seafloor. The world's record then had been 2,111 m (at a water depth of 3,462.8 m), achieved by riser-less drilling from the U.S.'s JOIDES Resolution off Ecuador in the Pacific Ocean near the Equator in 1993.

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Scientists of Kochi Institute for Core Sample Research, JAMSTEC, and Atmosphere and Ocean Research Institute, the University of Tokyo found that a remarkable number of microbial cells are metabolically "alive" in deep and ancient subseafloor sediments off the Shimokita peninsula of Japan in the northern Pacific. The scientists examined the microbial incorporation of stable isotope-labeled substrates at single cell-level using nanometer-scale secondary-ion mass spectroscopy (NanoSIMS) and found that over 10 million cells per cubic centimeter of microbes from deep subseafloor sediment were capable to assimilate carbon- and nitrogen-substrate at rates of one hundred thousand times slower than Escherichia.coli cells in the laboratory incubations. The results are the first time of quantitative evidence to show the metabolic potential of microorganisms in subseafloor biosphere, the most understudied ecosystem on Earth, This study is expected to lead to unveiling the role of subseafloor microorganisms on the global element cycle, evolution and adaptation in their environment.
The sediment sample was obtained by the shakedown expedition of deep sea drilling vessel Chikyu in 2006, at a site approximately 80 km off the coast of the Shimokita peninsula (water depth: 1,180 m) from a depth of 219 meters below the seafloor (mbsf).

The work is published online on October 11 in the Proceedings of the National Academy of Science of the United States of America (PNAS).

Researchers of JAMSTEC, Nagaoka University of Technology, The University of Tokyo and Kochi Institute for Core Sample Research of JAMSTEC, have successfully cultivated and isolated diverse subseafloor microbes including methanogens (methane-producing microbes), using a continuous-flow bioreactor that was originally developed for wastewater treatment.

To effectively activate seafloor microbes, researchers developed a new cultivation method using a traditional water treatment reactor. The incubation was carried out with cores collected from seabeds (water depth: 1.180 meters) off Hachinohe, northern Japan, during the shakedown expedition of the Deep-Sea Drilling Vessel Chikyu in 2006,
The results saw a successful enrichment and subsequent isolation of marine subseafloor microbes, including methanogens, which are known to be extremely difficult to culture in vitro.

In this study, Methanogens belonging to the genera Methanobacterium and Methanosarcina were detected concomitantly with methane production, along with a variety of unknown bacterial and archaeal species. The results are expected to provide clues, not only to clarifying microbial activity and carbon cycling in subseafloor sediments, but also to developing "green" technology to convert atmospheric carbon dioxide (CO2) into natural gas.

Their work is published online in The ISME Journal on June 9.

Drs. Fumio Inagaki and Yuki Morono, Geomicrobiology Group of the Kochi Institute for Core Sample Research (KOCHI), the Japan Agency for Marine-Earth Science and Technology, reported that remarkably abundant Archaea exist in global marine subsurface sediments, as a result of the collaboration between JAMSTEC and the University of Bremen (Prof. Kai-Uwe Hinrichs) in Germany. The population of two domains of life, Archaea and Bacteria, in marine subsurface was studied by intact polar lipids (IPLs) and DNA extracted from a variety of marine subsurface sediment samples, which included the core sediments collected by the deep-sea drilling vessel Chikyu off Japan.
Marine subsurface sediments cover approximately 70% of the Earth’s surface crust. Subsurface sediments was found to be the largest biosphere on Earth because of a large population of Archaea widely distributed in sediments, even in the deep marine subsurface over 300 m below the seafloor. The result contributes to the better understanding of the least explored deep sub-seafloor biosphere as well as their adaptation to the low energy subsurface environments and the evolution of life on our planet.

This is reported in Nature (online) on July 20.