1. Institute of Molecular Infection Biology, University of Würzburg , 97080 Würzburg, Germany
2. Molecular Ecology, Agroscope and SIB Swiss Institute of Bioinformatics , 8046 Zurich, Switzerland
3. Institute of Microbiology, University of Greifswald , 17489 Greifswald, Germany
4. Institute of Microbiology and Molecular Biology, University of Giessen , 35392 Giessen, Germany
5. Bioinformatics Group, Department of Computer Science, University of Freiburg , 79110 Freiburg, Germany