1. Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
2. Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA.
3. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
4. Pacific Northwest National Laboratory, Richland, WA 99352, USA.
5. Department of Mathematics, University of California, Riverside, Riverside, CA 92507, USA.