1. Max Planck Institute for Marine Microbiology, Microbial Genomics and Bioinformatics Research Group, Celsiusstr.1, 28359 Bremen, 2Jacobs University Bremen, School of Engineering and Sciences, Campusring 1, 28759 Bremen, 3Ribocon GmbH, D-28359 Bremen, Germany and 4Department of Microbial Ecology, University of Vienna, Althanstr. 14, 1090 Vienna, Austria