Principal Investigator: Professor Sharon L. Doty, College of Forest Resources

Co-P.I.: Professor James T. Staley, Dept. of Microbiology

University of Washington, Seattle, Washington, USA

Yeast were isolated from poplar trees growing in three locations. Three yeast isolates were able to grow on medium lacking nitrogen (ammonium and nitrate). There was no bacterial contamination as judged by microscopic, molecular, and chemical tests. The yeast strains incorporate 15N label when exposed to 15N2 gas, the total nitrogen content increases after growth in nitrogen-free medium, and they contain the nitrogenase gene. We are further studying these yeast isolates to verify that they are able to use atmospheric nitrogen. If they are, they would be the only eukaryotic organisms known to fix nitrogen.