1 Department of Microbiology, Technical University München, D-85354 Freising, Germany.
2 Max-Planck Institute for Marine Microbiology, D-28359 Bremen, Germany.
3 Marine Microbiology Group, Department of Ecology and Marine Resources, Mediterranean Institute for Advanced Studies (IMEDEA, CSIC-UIB), E-07190 Esporles, Illes Balears, Spain.