Introductory comments |
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Authors: | William C. Ghiorse Guest Editor Frank J. Wobber Geologist |
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Affiliation: | 1. Department of Microbiology , Cornell University , 405 Stocking Hall, Ithaca, NY, 14853–7201;2. Office of Energy Research, U.S. Department of Energy , Office of Health and Environmental Research , Washington, DC, 20545 |
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Abstract: | Abstract Associated microorganisms have been described in numerous marine sponges. Their metabolic activity, however, has not yet been investigated in situ. We quantified for the first time microbial processes in a living sponge. Sulfate reduction rates of up to 1200 nmol cm?3d?1 were measured in the cold-water bacteriosponge Geodia barretti . Oxygen profiles and chemical analysis of sponge tissue and canal water revealed steep oxygen gradients and a rapid turnover of oxygen and sulfide, dependent on the pumping activity of the sponge. Identification of the microbial community with fluorescently labelled oligonucleotide probes (FISH) indicates the presence of sulfate-reducing bacteria belonging to the Desulfoarculus/Desulfomonile/Syntrophus -cluster in the choanosome of this sponge. Analysis of lipid biomarkers indicates biomass transfer from associated sulfate-reducing bacteria or other anaerobic microbes to sponge cells. These results show the presence of an anoxic micro-ecosystem in the sponge G. barretti, and imply mutualistic interactions between sponge cells and anaerobic microbes. Understanding the importance of anaerobic processes within the sponge/microbe system may help to answer unsolved questions in sponge ecology and biotechnology. |
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Keywords: | Geodia barretti microelectrodes oxygen profiles Porifera sponge associated microbes sulfate reduction rates SRR symbiosis |
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