Researchers are particularly interested in SAR11, Giovannoni said, because of the critical role it plays in geochemistry. Photosynthesis is a process used by plants to convert sunlight energy into organic molecules, creating the foundation of the food chain and producing oxygen. About half of photosynthesis and the resulting oxygen on Earth are produced by algae in the ocean, and microbes like SAR11 recycle organic carbon - producing the nutrients needed for algal growth.
"Ultimately, SAR11 through its sheer abundance plays a major role in the Earth's carbon cycle," Giovannoni said. "Quite simply, this is something we need to know more about. SAR11 is a major consumer of the organic carbon in the oceans, which nearly equals the amount of carbon dioxide in the atmosphere. The carbon cycle affects all forms of plant and animal life, not to mention the atmosphere and fossil fuel formation."
SAR11 was first discovered at OSU in 1990. Since then researchers have learned that populations of SAR11 increase during the summer and decrease during the winter, in a cycle that correlates to the ebb and flow of organic carbon in the ocean surface. Molecular probes, gene cloning, sequencing techniques and other tools have been used in this exploration.