1. University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
2. Department of Microbiology, 527 Biological Sciences Building, University of Georgia, Athens, GA 30602-2605, USA
3. DOE Joint Genome Institute, 1 Cyclotron Rd, Berkeley, CA 94720, USA