Under Pressure: Microbial Carbon Sequestration in the Deep North Atlantic Ocean

Microorganisms living in the deep sea (>200 m water depth) have the potential to play important roles in shaping global chemistry and climate by producing and consuming greenhouse gases and cycling nutrients required for all marine life. However, the activity and physiology of these cells are poorly characterized to date, largely due to sample inaccessibility and the technical challenges of maintaining pressure-adapted, slow-growing microorganisms in the laboratory. This project leverages a French sampling expedition to the North Atlantic Ocean and recently developed sampling and analysis technologies to study the metabolism and activity of deep-sea microorganisms. Specifically, we will measure growth rates of individual deep-sea cells and characterize their metabolisms while maintaining in situ pressure. Our hypothesis is that deep-sea microbial activity, and specifically chemoautotrophy (a metabolism analogous to photosynthesis but in the dark), has been underestimated to date and therefore inaccurately represented in global models. Our experiments will provide new insights into the biology and the chemistry of the deep sea, and therefore the limits of life on Earth and the potential for deep-sea microbes to mitigate climate change. American and French scientists and students will work together in sampling, experiments, analysis, and manuscript preparation as part of this work.