Carbon Fixation Pathways From the Marine Dark Biosphere
Abstract
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2020
- Accession Number
- AD1100713
Entities
People
- Bradley Ringeisen
- Christina Krute
- Dhanya Haridas
- Justin C Biffinger
- Leila Hamdan
- Lisa Fitzgerald
- Preston Fulmer
- Thomas J Boyd
- Yukari Maezato
Organizations
- United States Naval Research Laboratory