1. Radboud Institute of Biological and Environmental Sciences, Microbiology Cluster, Radboud University, Nijmegen, Netherlands
2. Soehngen Institute of Anaerobic Microbiology, Nijmegen, Netherlands
3. Microcosm Earth Center, Philipps-Universität Marburg and Max Planck Institute for Terrestrial Microbiology, Marburg, Germany