1. Swiss Federal Institute of Technology Lausanne (EPFL), School of Environmental Sciences, Architecture and Civil Engineering, Laboratory of Soil Science, CH-1015 Lausanne, Switzerland, UFZ Centre for Environmental Research Leipzig-Halle, Department of Environmental Microbiology, D-04318 Leipzig, Germany, and Catholic University of Louvain (UCL), B-1348 Louvain-la-Neuve, Belgium