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The microbial community structure of different permeable sandy sediments characterized by the investigation of bacterial fatty acids and fluorescence in situ hybridization

Authors

  • S. I. Bühring,

    Corresponding author
    1. Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany.
      *E-mail solveig.buehring@uni-bremen.de; Tel. (+49) 421 2188934; Fax (+49) 421 2188664.
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    • Present address: Research Center Ocean Margins, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany.

  • M. Elvert,

    1. Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany.
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    • Present address: Research Center Ocean Margins, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany.

  • U. Witte

    1. Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany.
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*E-mail solveig.buehring@uni-bremen.de; Tel. (+49) 421 2188934; Fax (+49) 421 2188664.

Summary

This study describes the microbial community structure of three sandy sediment stations that differed with respect to median grain size and permeability in the German Bight of the Southern North Sea. The microbial community was investigated using lipid biomarker analyses and fluorescence in situ hybridization.  For  further  characterization  we  determined the stable carbon isotope composition of the biomarkers. Biomarkers identified belong to different bacterial groups such as members of the Cytophaga-Flavobacterium cluster and sulfate-reducing bacteria (SRB). To support these findings, investigations using different  fluorescent  in  situ hybridization  probes were performed, specifically targeting Cytophaga-Flavobacterium, γ-Proteobacteria and different members of the SRB. Depth profiles of bacterial fatty acid relative abundances revealed elevated subsurface peaks for the fine sediment, whereas at the other sandy sediment stations the concentrations were less variable with depth. Although oxygen penetrates deeper into the coarser and more permeable sediments, the SRB biomarkers are similarly abundant, indicating suboxic to anoxic niches in these environments. We detected SRB in all sediment types as well as in the surface and at greater depth, which suggests that SRB play a more important role in oxygenated marine sediments than previously thought.

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