Studies of the marine archaeon (Nitrosopumilus maritmus) by investigators at the University of Washington established that ammonia-oxidizing Archaea (AOA) are capable of growing under the extreme nutrient limited conditions characteristic of the open ocean, using ammonia and carbon dioxide as sole sources of energy and carbon. This remarkable feature and the high abundance of AOA among marine bacterioplankton together suggest they play a fundamental role in marine nitrogen and carbon cycles, and also compete with marine phototrophs for ammonia. In addition to their remarkable affinity for ammonia, the genome sequence of N. maritimus points to a capacity to make novel phosphorous compounds that may contribute to methane release from marine surface waters, the use of a copper-based respiratory system that could provide ecological advantage in iron-limited ocean waters, a novel mechanism of cell division, and a high adaptive capability conferred by an unusually large number of transcription factors. These investigators will collaborate with an international group of scientists to determine how AOA are able to grow on ammonia at vanishing low concentrations, maintain copper homeostasis, respond to changing environmental conditions, and possibly contribute to atmospherically significant gases.
Broader Impacts. Marine systems are increasingly impacted by acidification and by atmospheric inputs of reactive nitrogen. Since these changes greatly alter nitrogen available to microorganisms, the research will advance understanding of the effects that acidification and anthropogenic nitrogen inputs are having on major ocean processes. The project will train one graduate student in environmental science and 1-3 undergraduates through mentoring by senior laboratory personnel. A postdoctoral associate will receive additional professional training through participation in the University of Washington Postdoctoral Association (UWPA), offering workshops in grant writing, teaching, publishing, oral communication, directing a laboratory, time management, crafting personal professional development plans, and faculty applications and hiring. The project will also serve as a vehicle for more general science education, taking advantage of existing outreach programs to promote better understanding by high school teachers and students of the critical role of microorganisms in global nutrient cycles.
