Details are now emerging about a microbial metabolic pathway that
helps solve the mystery of how certain bacteria do this in the dark
ocean. These research results, which are enabling a better understanding
of what happens to the carbon that is fixed in the oceans every year,
were published by a team of researchers, including those from the U.S.
Department of Energy (DOE) Joint Genome Institute (JGI), in the Sept. 2,
2011 edition of Science.
Bigelow’s Dashiell Masland working with a Tecan Freedom EVO robotic liquid handler.
Carbon fixation in the dark ocean has so far been attributed
primarily to the Archaea, single-celled organisms that often live in
extreme environmental conditions. In this region of the ocean, the
bacteria living there were thought to rely on organic compounds for both
energy and carbon. According to DOE JGI collaborator Ramunas
Stepanauskas, Director of the Bigelow Laboratory Single Cell Genomics
Center and senior author of the Science paper, "Previous
oceanographic models suggested that Archaea do not adequately account
for the amount of carbon that is being fixed in the dark ocean. Our
study discovered specific types of Bacteria rather than Archaea, and
their likely energy sources that may be responsible for this major,
unaccounted component of the dark ocean carbon cycle."
To overcome the challenge that had hindered studies of deep ocean
microbes, which have not yet been cultivated in the laboratory,
researchers employed innovative single-cell genomics techniques, where
DOE JGI's Tanja Woyke and Alexander Sczyrba, Bigelow Laboratory's
Ramunas Stepanauskas and their teams are among the pioneers. Study
co-author Woyke explained, "After we sequenced the genomes of single
cells that were isolated by our colleagues at Bigelow, it was possible
to verify the predominant bacterial lineages capable of trapping carbon
in this deep underwater region. "This study represents a pristine
example for the use of single cell genome sequencing to decipher the
metabolic capabilities of uncultured natural microbial consortia,
providing a powerful complement to metagenomics."
Stepanauskas attributed the success of the project to the combined
efforts of the DOE JGI, the Bigelow Laboratory, the Monterey Bay
Aquarium Research Institute, the University of Vienna, and MIT. "This is
the first application of a single-cell genomic approach to the deep
ocean, one of the largest and least known biomes on the planet,"
emphasized David Kirchman, Harrington Professor of Marine Biosciences at
the University of Delaware. "The paper radically changes our view about
how microbes gain energy and flourish in the oceans.
From sciencedaily
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