Do We Have a Quorum?

During a presentation to the MIT Knight Science Journalism Fellows in September, WHOI biogeochemist Tracy Mincer described how chemical “conversations” among bacteria affect carbon cycling in the ocean. The image on the screen shows a tiny clump of carbon-rich detritus and whole cells that Mincer harvested from a particle trap set in Clayoquot Sound, British Columbia. Embedded in the clump are dozens of fluorescent-stained microbes. Mincer and colleagues Laura Hmelo and Ben Van Mooy found that bacteria in the clumps secrete chemical signals that can be detected by other bacteria. When enough signal is present, the bacteria exude enzymes that break down the organic matter, ultimately respiring it to carbon dioxide. The study provided the first evidence that bacterial communication plays a role in Earth’s carbon cycle and, hence, on climate. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)