Carbon Fixation Pathways From the Marine Dark Biosphere
Technical Report,01 Oct 2015,30 Sep 2019
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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The dark marine biosphere DMB is an environment that is permanently separated from light-driven energy production mechanisms. Survival in the DMB is challenging no light for photocatalytic processes, extremes in temperature, oxygen limitation, scarce sources of energy, and high concentrations of carbon dioxide. Despite these extremes, 70 of the Earths microorganisms live in and are adapted to generate cellular energy in the sub-seafloor sediments 1, yet only 5 of the sea floor has been explored 2. The DMB also covers more than two-thirds of the Earths area and is alternatively known as the most isolated CO2 sink of the Earth 3. This biosphere has the largest capacity to absorb and convert CO2 based on not just its surface area alone but also passive and active pumping mechanisms from microbial activity in the sediment and surrounding water. Thus, the microbiome all microorganisms, their genetic elements and their abiotic interactions of the DMB must adapt to this changing concentration of CO2. Therefore, this biosphere is the greatest untapped resource for the discovery of new dark carbon fixation pathways and carbon fixing microorganisms. In addition, how this microbiome fluctuates could provide evidence for how some of the most untouched areas on earth are responding to changing CO2 levels. Nevertheless, in the last decade, three new carbon fixation enzyme systems have been discovered in the dark biosphere and given the vastness of the uncultured majority, the probability for discovery of more carbon fixation pathways is extremely high. Despite the demonstrated discovery potential of the dark biosphere, a vast majority of bioenergy studies remain focused on harnessing the process and byproducts e.g. cellulosic biomass of oxygenic photosynthetic carbon fixation.
- Inorganic Chemistry
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy