Integration of Deep Ocean Benthic Sampler Technology with Microbial Biogeochemistry of Methane Seeps and Isolation of Piezophilic Deep-Sea Sediment Microbes

Collaborators:
Craig Taylor (Biology Dep., WHOI)
Richard Sheryll (American Museum of Natural History, New York)
Rob Desalle (American Museum of Natural History, New York)

Bacteria and archaea account for half the biomass on Earth and drive major biogeochemical cycles, due to their metabolic diversity and ability to catalyze a broad spectrum of chemical reactions. They form the basis of various ecosystems, yet our understanding of the functioning of the microbial communities in many of these environments is still limited. This is particularly true for deep ocean sediments, which harbor a significant portion of the microbial biosphere existing under elevated hydrostatic pressure (up to 110 MPa; 1086 atm) and low temperatures. This prevents many, if not most microorganisms from these environments from being cultured in the laboratory, suggesting that we have only scratched the surface of the metabolic potential and the extent of physiological diversity of the microbial communities inhabiting these environments. From a biogeochemical standpoint, hydrostatic pressure can also dramatically influence chemical gradients within microbial ecosystems, in particular in gas- and gas-hydrate bearing deep-sea sediments. Preservation of sediment samples from these environments is a particular challenge in that the time between sampling and retrieval can be hours and changes in pressure, temperature can result in substantial out-gassing that destroys the structural integrity of the retrieved sediment sample as well as changes the composition and activity of the contained microbial communities.

The Deep Ocean Benthic Sampler (DOBS) possesses a capability that is unique to the fields of deep-sea microbial ecology and biogeochemistry, the ability to obtain a contamination-free core and preserve in situ conditions of pressure and temperature upon retrieval to the ship. The application of proposed mechanisms for obtaining multiple sub-cores at various depth horizons within the retrieved core samples, in the absence of decompression, permits in concert a) accurate assessment of the gaseous and chemical gradients within the core without being disturbed by the “homogenizing” out-gassing that typically occurs in such samples when collected by conventional coring operations and b) the phylogenetic (DNA, rRNA, functional (mRNA) molecular study and culture of the resident microbiota using high pressure hardware available at WHOI. Here, we propose to develop DOBS into a routine instrument that can be used by the oceanographic community to obtain undisturbed sediment cores maintained under in situ conditions for biogeochemical and microbiological analyses.

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This project is funded by the Ocean Technology and Interdisciplinary Coordination program within the Ocean Science Disvision of NSF.