Supplementary material to “Exploring the Deep Biosphere: Probing Microbial Systems at Earth’s Extremes”

Patricia Sobecky, School of Biology, Georgia Institute of Technology, Atlanta

Citation:
Sobecky, P. (2007), Exploring the deep biosphere: Probing microbial systems at Earth’s extremes, Eos Trans. AGU, 88(34), 336. [Full Article (pdf)]

Deep drilling of marine sediments and oceanic crust offers a unique opportunity to explore how life persists and evolves in the Earth’s deepest subsurface ecosystems. Resource availability deep beneath the seafloor may impose constraints on microbial growth and dispersal patterns that differ greatly from the surface world. Processes that mediate microbial evolution and diversity may also be very different in these habitats. Communities in parts of the deep subsurface may resemble primordial microbial ecosystems, and may serve as analogues of life on other planets that have, or once had, water. In short, the deep biosphere is one of the least explored biomes on Earth and deserves intense exploration.

The Integrated Ocean Drilling Program (IODP) provides tremendous opportunities to understand the abundance, activity, diversity, and limits of deep-ocean subseafloor microbial communities. The workshop “Exploring Subseafloor Life with IODP” was convened to solicit recommendations and guidance on scientific issues and technical challenges for exploring microbial life in the deep subseafloor. The 90 participants included molecular biologists, microbiologists, microbial ecologists, geologists, biogeochemists, drilling experts, and engineers.

Daily breakout sessions focused on four key scientific areas: (1) biogeography; (2) genes, cells, populations and communities; (3) habitability, and (4) technology:

Biogeography: Four aspects were determined particularly important. The first is a thorough characterization of deep subsurface habitats and their microbiota. Second, spatial and temporal controls on diversity need to be explored. Third, we need to know the mechanisms and rates of evolution under potentially slow growth, low predation, and severe energy limitation conditions. Finally, the extent to which the deep biosphere is generally connected to the surface biosphere is unclear.
Genes, cells, populations, and communities: It is recommended that microscopic observations of sediment and rocks be expanded to include modern cell-staining procedures. Applying molecular microbial ecology methods will determine overall genetic potential as well as link this potential to gene function and expression.
Habitability: The geological and biological processes that control habitable environments and that fuel growth of microbial communities in deep subseafloor environments remain to be determined, but the most important parameters can be modeled with appropriate field measurements. Discovery of the limits to life and habitability in these environments should be pursued by using a variety of potential signatures, such as metabolic and enzymatic activities, RNA, and intact polar lipids.
Technology: The primary technology objective is to assure that a specific regimen of coring and sampling handling will be maintained to facilitate microbiological characterization. The participants recommended establishing an IODP microbiological standardized sampling protocol through appropriate modifications of existing sampling and analytical protocols. All data generated as part of this standardized sampling should be integrated with the existing IODP database structure.

The International Workshop “Exploring Subseafloor Life with the Integrated Ocean Drilling Program” was held 3–5 October 2006 in Vancouver, British Columbia. The workshop was co-sponsored by IODP Management International and Joint Oceanographic Institutions, Inc. A full meeting report will be available in the near future at http://www.iodp.org/.

Authors:

Patricia Sobecky (corresponding author): School of Biology, Georgia Institute of Technology, 310 Ferst Drive, Atlanta GA 30332-0230 USA; E-mail: patricia.sobecky@biology.gatech.edu
Wolfgang Bach: Fachbereich 5 Geowissenschaften, Universität Bremen, Gebäude GEO, Raum 5340, Klagenfurter Straße, D-28359 Bremen Germany; E-mail: wbach@uni-bremen.de
Heribert Cypionka: Institut für Chemie und Biologie des Meeres, Universität Oldenburg, Fakultät 5, D-26111 Oldenburg Germany; E-mail: cypionka@icbm.de
Steven D'Hondt: Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett RI 02882 USA; E-mail: dhondt@gso.uri.edu
Katrina Edwards: Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, AHF 203, Los Angeles CA 90089-0371 USA; E-mail: kje@usc.edu
Tim Ferdelman: Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, D-28539 Bremen Germany; E-mail: tferdelm@mpi-bremen.de
Philippe Gaillot: Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama Institute for Earth Sciences, 3173-25 Showa-machi, Kanazawa-ku, Yokohama Kanagawa 236-0001 Japan; E-mail: gaillotp@jamstec.go.jp
Julie Huber: Josephine Bay Paul Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole MA 02543 USA; E-mail: jhuber@mbl.edu
Fumio Inagaki: Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Monobe B200, Nankoku, Kochi 783-8502 Japan; E-mail: inagaki@jamstec.go.jp
Kenji Kato: Department of Geosciences, Shizuoka University, 836 Oya Shizuoka 422-8529 Japan; E-mail: skkato@ms.ipc.shizuoka.ac.jp
Paul Kemp: School of Ocean and Earth Science, University of Hawaii, Honolulu HI 96822 USA; E-mail: paulkemp@hawaii.edu
R. John Parkes: School of Earth, Ocean and Planetary Sciences, University of Cardiff, Main Building, Cardiff CF10 3AT UK; E-mail: J.Parkes@earth.cf.ac.uk
Mitch Sogin: Marine Biological Laboratory, 7 MBL Street, Woods Hole MA 02543 USA; E-mail: sogin@mbl.edu
Ken Takai: Subground Animalcule Retrieval (SUGAR) Program, Japan Agency for Marine-Earth Science & Technology, 2-15 Natsushima-cho, Yokosuka 237-0061 Japan; E-mail: kent@jamstec.go.jp
Andreas Teske: UNC Chapel Hill, Department of Marine Sciences, Chapman Hall 351, Chapel Hill NC 27599 USA; E-mail: teske@email.unc.edu