1. Department of Plant and Microbial Biology, University of Minnesota , 1479 Gortner Avenue, Saint Paul, Minnesota 55108 , United States
2. Microbial Ecology Group, Department of Biology, Lund University , Naturvetarvägen 22362, Lund , Sweden
3. Laboratory of Environmental Microbiology, Institute of Microbiology of the Czech Academy of Sciences , Vídenská 1083, Prague 142 20 , Czech Republic