1. Max Planck Institute for Marine Microbiology; Celsiusstrasse 1 D-28359 Bremen Germany
2. University of Bremen, MARUM - Center for Marine Environmental Sciences, Petrology of the Ocean Crust group; Leobener Str. D-28359 Bremen Germany
3. Harvard University, Department of Organismic & Evolutionary Biology; 16 Divinity Avenue Cambridge MA 02138-2020 USA
4. University of Bergen, Department of Earth Science and Centre for Geobiology; Postboks 7803 N-5020 Bergen Norway