The Characterization and Isolation of Novel Phototrophic and Heterotrophic Diazotrophs in the Atlantic Ocean


Nitrogen is a critical element for life, and, as dinitrogen or nitrogen gas, makes up 80% of the air we breathe; however, most organisms - including eukaryotic plants and animals - are unable to utilize nitrogen in this form.  Instead, diverse prokaryotes use an enzyme called nitrogenase to catalyze biological nitrogen fixation (BNF), which converts the nitrogen into a biologically available form.  Diazotrophs are a specific group of bacteria and Archaea which express the nitrogenase enzyme.  

We are interested in understanding temporal and spatial variations in the diazotrophic community in the North Atlantic and the Bedford Basin, as well as the environmental factors influencing these variations. Environmental parameters that have been proposed to control diazotrophic distribution include temperature, water column stability, upward diffusive fluxes of nutrients, light, and input of iron (Fe) and phosphate (P) via atmospheric mineral dust deposition.  Attempts will be made to cultivate diazotrophic microorganisms from both the North Atlantic and the Bedford Basin, which will then serve as molecular models for further investigation. As part of the characterization of diazotrophs, a new method to measure BNF rates will be developed.