SGER: Distribution of Photoheterotrophic Bacteria in the Ocean

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A new type of bacteria in the ocean was discovered this past year using in?situ infrared fluorescence measurements. These cells, termed aerobic, anoxygenic photoheterotrophs, or AAPs, are capable of using sunlight and/or carbon sources for energy. They can fix C02, but do not produce oxygen as traditional photosynthesizers do. They were shown to live in coastal ocean waters and in the Northeastern Pacific Ocean. The ecological role and importance of AAPs is not known. In current carbon models they are confounded with heterotrophic bacteria, yet may play a very different role. This project, a small grant for exploratory research, will analyze samples collected from 3 recent research cruises in the NW Atlantic for counts of AAP cells across seasons and across a trophic gradient from productive, coastal Maine, Gulf of Maine, and Georges Bank waters to offshore oligotrophic waters of the Sargasso Sea. This project will provide some of the first quantitative estimates of AAPs in different marine ecosystems and over different seasons, and will give the first indication of the potential ecological importance of this newly discovered microbial form. The findings from this study should have broad significance in understanding ocean ecology and biogeochemical cycling in the oceans.