Seafloor bacteria are multi-tasking with the carbon cycle


Scientists have long known that microorganisms can use one of two different methods to convert carbon dioxide into a form that living things can use for energy. What they didn’t know until recently is that at least one form of bacteria can switch between these two “carbon fixation” pathways or use them both at the same time—a fundamental discovery for scientists who believe such bacteria played a role in the evolution of life on Earth. Past research has shown that symbiotic bacteria live inside tubeworms and provide energy to their hosts in exchange for a safe place to live. Biologists knew this marriage was a good one, as the tubeworm is the fastest-growing marine invertebrate known to exist. But they did not know the details of how the bacteria make the energy because they could not culture the bacteria successfully in the lab. WHOI microbiologist Stefan Sievert was part of a research team—led by Thomas Schweder and Stephanie Markert of the Institute of Marine Biotechnology in Germany—that studied the bacteria’s genome to discover how these microbes switch back and forth between both carbon-fixing methods—the “Calvin cycle” and the reductive tricarboxyclic (rTCA) cycle—to adapt to fast-changing environmental conditions on the deep seafloor.

For Immediate Release

Media Relations Office

(508) 289-3340


Scientists have discovered that the endosymbiotic bacteria living inside tubeworms are capable of using two fundamentally different means to generate organic carbon--both the "Calvin" cycle and the reductive tricarboxylic acid (rTCA) cycle. (Photo by Woods Hole Oceanographic Institution)

See Also

Stefan Sievert's Lab

The Sievert Microbial Ecology & Physiology Lab studies the composition and function of microbial communities, with the goal to understand the relationship between microorganisms and their biogeochemical transformations. Special interests include chemosynthetic processes that are important in a variety of environments, including hydrothermal systems, oxygen minimum zones, and sulfidic marine sediments.