1. Water Research Institute; IRSA-CNR; via Salaria km 29,300, 00015 Monterotondo Roma Italy
2. University of Vienna, Department of Microbiology and Ecosystem Science; Althanstrasse 14 A-1090 Vienna Austria
3. University of South Bohemia, Faculty of Science; Branišovská 31 370 05 České Budějovice Czech Republic
4. Masaryk University, Department of Botany and Zoology, Faculty of Science; Kotlářská 2 61137 Brno Czech Republic
5. Max Planck Institute for Marine Microbiology; Celsiusstrasse 1 D-28359 Bremen Germany