Studies of microorganisms and their activity deep down in the seabed require advanced coring technology and rigorous contamination control. Sediment samples must be taken up from tens to hundreds of meters below seafloor without contamination by bacteria from the surface world. This is now indeed possible through the international Integrated Ocean Drilling Program (IODP) which provides access to such sediments throughout the world oceans.

Scientific drilling is not exactly a sterile operation. Yet, sediment cores with uncontaminated interior can be retrieved in transparent plastic liners and sectioned by scientists for microbiological and biogeochemical research.  The consistent recovery and enumeration of cells in carefully cored marine sediments are accompanied by rigorous contamination controls:  a) a dissolved perfluorocarbon tracer is introduced into the seawater which is pumped down into the drill hole to flush out suspended sediment, and b) bacterial-size fluorescent beads are smeared around the cored sediment to check for possible penetration of micro-particles into the precious microbiology samples. Only non-contaminated sediment is used for microbiology research.

Center staff on-board IODP-drilling expeditions

Since its establishment in 2007, the Center for Geomicrobiology has participated on board in five drilling expeditions organized by the IODP:

• #323 Bering Sea Paleoceanography 2009,
• #327 Juan de Fuca Hydrogeology in the Northeast Pacific 2010,
• #329 South Pacific Gyre Subseafloor Life 2010,
• #336 Mid-Atlantic Ridge Microbiology 2011
• #337 Deep Coalbed Biosphere off Shimokita 2012.

2012: Pacific Ocean

The expedition #337 to the North Pacific offshore Shimokita Peninsula on board the Japanese vessel, Chikyu, explored 50 million years old coal layers that are buried two kilometers deep beneath the seafloor. Among the scientific questions is whether, after so many years of burial and degradation, the high concentration of organic matter in the lignite still provides extra food and energy to sustain microbial communities. Due to the geothermal gradient of ca 30°C per km, gradual heating may accelerate the bioavailability of this buried hydrocarbon reservoir. Microbiologists and geochemists who were among the Science Party now study the diversity of microorganisms and analyze how this unique chemical environment affects their metabolic activity.

2013: Baltic Sea

In 2013, the head of the center will be a co-chief scientist on expedition #347 Baltic Sea Paleoenvironment. For the first time there will be deep scientific drilling in the Baltic Sea with several of the drill sites located in Danish waters. The targeted sediments cover the past 140,000 years during which Scandinavia went through two major periods of glaciation. These dramatic variations in climate are preserved in the sediment archive under the Baltic Sea and witness the large environmental shifts in sedimentation, salinity, temperature, productivity and oxygen. Studies of the microbial communities and of extant and fossil DNA will reveal how subsurface life has adapted to conditions of today and, possibly, how it adapted to conditions of the past.