1. Los Alamos National Laboratory; Bioscience Division MS888; P.O. Box 1663 Los Alamos NM 87545
2. Universität Hamburg, Biozentrum Klein Flottbek, Mikrobiologie & Biotechnologie; D-22609 Hamburg Germany
3. Departments of Microbiology and Crop and Soil Science; Oregon State University; Corvallis OR 97331-3804