It's broadly understood that the world's oceans play a crucial role in the global-scale cycling and exchange of carbon between Earth's ecosystems and atmosphere. Now scientists at Scripps Institution of Oceanography at UC San Diego have taken a leap forward in understanding the microscopic underpinnings of these processes.
When phytoplankton use carbon dioxide to make new cells, a substantial portion of that cellular material is released into the sea as a buffet of edible molecules collectively called "dissolved organic carbon." The majority of these molecules are eventually eaten by microscopic marine bacteria, used for energy, and recycled back into carbon dioxide as the bacteria exhale. The amount of carbon that remains as cell material determines the role that ocean biology plays in locking up atmospheric carbon dioxide in the ocean.
Thus, these "recycling" bacteria play an important role in regulating how much of the planet's carbon dioxide is stored in the oceans. The detailed mechanisms of how the oceans contribute to this global carbon cycle at the microscopic scale, and which microbes have a leadership role in the breakdown process, are complex and convoluted problems to solve.
In a study published in the Proceedings of the National Academy of Sciences, Scripps scientists have pinpointed a bacterium that appears to play a dominant role in carbon consumption. Scripps's Byron Pedler, Lihini Aluwihare, and Farooq Azam found that a single bacterium called Alteromonas could consume as much dissolved organic carbon as a diverse community of organisms.
"This was a surprising result," said Pedler. "Because this pool of carbon is comprised of an extremely diverse set of molecules, we believed that many different microbes with complementary abilities would be required to breakdown this material, but it appears that individual species may be pulling more weight than others when it comes to carbon cycling."
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University of California - San Diego