Research in our laboratory group focuses on how microorganisms control the availability of nitrogen, a critical element in all life as we know it. Nitrogen, a major plant nutrient, is transformed from one form to another by microorganisms, and moves between habitats. A large reservoir of nitrogen on Earth resides in the air we breath: 80% of the atmosphere is nitrogen gas. Nitrogen gas, or dinitrogen (2 nitrogen atoms triple bonded together) has historically been thought to be unavailable to most organisms, in particular the eukaryotic plants and animals. Many diverse prokaryotic microorganisms have the ability to fix nitrogen from the atmosphere into a biologically available form. Biological nitrogen fixation is catalyzed by an enzyme, called nitrogenase. Since most of the microorganisms in the natural environment have yet to be cultivated, we study the microorganisms in the environment that fix nitrogen by looking for the genes and proteins involved in nitrogen fixation. And recently our work has focused more on the cultivated species, Braarudosphaera bigelowii, the first discovered eukaryotic nitrogen fixing organism. This broadly distributed species of marine eukaryotic phytoplankton contains a nitrogen-fixing organelle, or nitroplast, formerly known as UCYN-A or Candidatus Atelocyanobacterium thalassa.