Widespread occurrence of two carbon fixation pathways in tubeworm endosymbionts: lessons from hydrothermal vent associated tubeworms from the Mediterranean Sea

1 GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany 2 Water Technology Center Karlsruhe, Karlsruhe, Germany 3 Institut fur Geologie und Palaontologie, Westfalische Wilhelms-Universitat Munster, Munster, Germany 4 Institut fur Geowissenschaften, Christian – Albrechts – Universitat Kiel, Kiel, Germany 5 Mueller Laboratory, Department of Biology, The Pennsylvania State University, University Park, PA, USA