1. Institute for Genomic Biology, University of Illinois, 1206 West Gregory, Urbana, IL 61801, USA.
2. Department of Microbiology, University of Illinois, 601 South Goodwin Avenue, Urbana, IL 61801, USA.
3. Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana–Champaign, 600 South Matthews Avenue, Urbana, IL 61801, USA.
4. Department of Civil and Environmental Engineering, University of Washington, 302 More Hall, Box 352700, Seattle, WA 98195–2700, USA.