1. Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany.
2. Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, UK.
3. Department of Microbiology and Ecosystem Science, University of Vienna, 1090 Vienna, Austria.
4. Department of Microbiology, Institute for Water and Wetland Research, Radboud University, 6525 AJ Nijmegen, Netherlands.
5. Section Microbiology, Biocenter Klein Flottbek, University of Hamburg, 22609 Hamburg, Germany.