Aquatic Sciences Meeting, Albuquerque 2001

SS14 Microbial Diversity (Disciplinary Connections)

Date: Monday, February 12, 2001, Time: 4:00:00 PM

Location: Brazos

Dubilier, N, , Max Planck Institute of Marine Microbiology, Bremen, Germany, ndubilie@mpi-bremen.de

Mülders, C, , Max Planck Institute of Marine Microbiology, Bremen, Germany, cmuelder@mpi-bremen.de

de Beer, D, , Max Planck Institute of Marine Microbiology, Bremen, Germany, dbeer@mpi-bremen.de

Ferdelman, T, , Max Planck Institute of Marine Microbiology, Bremen, Germany, tferdelm@mpi-bremen.de

Wagner, M, , Technical University of Munich, Munich, Germany, wagner@mikro.biologie.tu-muenchen.de

Giere, O, , University of Hamburg, Hamburg, Germany, fb5a129@nw01.rrz.uni-hamburg.de

Amann, R, , Max Planck Institute of Marine Microbiology, Bremen, Germany, ramann@mpi-bremen.de

ENDOSYMBIOTIC SULFATE-REDUCING AND SULFIDE-OXIDIZING BACTERIA COEXIST IN A GUTLESS MARINE WORM

Gutless marine oligochaetes are remarkable for their symbioses with multiple bacterial endosymbionts. Phylogenetic analyses and in situ hybridization based on 16S rRNA have been instrumental in unraveling the phylogenetic diversity of these unculturable endosymbionts. In one host species, Olavius algarvensis, two distinct bacterial symbionts belonging to the gamma and delta subclass of the Proteobacteria coexist in close proximity to each other. Using a combination of molecular, physiological, and biogeochemical techniques we show that the gamma proteobacterial symbiont is a chemoautotrophic, sulfide-oxidizer and the delta proteobacterial symbiont is a sulfate-reducer, indicating the presence of a syntrophic sulfur cycle. Internal sulfate reduction rates from the sulfate-reducing symbionts are as high as those measured in microbial mats, while external sulfide concentrations in the worm's habitat are extremely low. Thus, this chemoautotrophic host appears to be independent of the uptake of reduced sulfur compounds from the environment, having internalized its sulfide source in the form of a sulfate-reducing bacterial symbiont.

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Aquatic Sciences Meeting, Albuquerque 2001

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