1. Max Planck Institute for Terrestrial Microbiology Karl-von-Frisch-Straße 10 35043 Marburg Germany
2. Department of Plant and Microbial Biology University of Minnesota Twin Cities, St. Paul Minnesota USA
3. Laboratory of Inorganic Synthesis and Catalysis Institute of Chemical Sciences and Engineering Ecole Polytechnique Fédérale de Lausanne (EPFL) ISIC-LSCI, BCH 3305 Lausanne 1015 Switzerland