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To What Extent Do Food Preferences Explain the Trophic Position of Heterotrophic and Mixotrophic Microbial Consumers in a Sphagnum Peatland?

Jassey, Vincent ; Meyer, Caroline ; Dupuy, Christine ; Bernard, Nadine ; Mitchell, Edward ; Toussaint, Marie-Laure ; Metian, Marc ; Chatelain, Auriel ; Gilbert, Daniel

In: Microbial Ecology, 2013, vol. 66, no. 3, p. 571-580

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    Title
    • To What Extent Do Food Preferences Explain the Trophic Position of Heterotrophic and Mixotrophic Microbial Consumers in a Sphagnum Peatland?
    Author
    • Jassey, Vincent. UMR CNRS/UFC 6249, Laboratoire Chrono-Environnement, Université de Franche-Comté, 25211, Montbéliard Cedex, France
    • Meyer, Caroline. UMR CNRS/UFC 6249, Laboratoire Chrono-Environnement, Université de Franche-Comté, 25211, Montbéliard Cedex, France
    • Dupuy, Christine. UMR CNRS 7266, Laboratoire Littoral Environnement et Sociétés, Université de La Rochelle, 17000, La Rochelle, France
    • Bernard, Nadine. UMR CNRS/UFC 6249, Laboratoire Chrono-Environnement, Université de Franche-Comté, 25211, Montbéliard Cedex, France
    • Mitchell, Edward. Laboratory of Soil Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland
    • Toussaint, Marie-Laure. UMR CNRS/UFC 6249, Laboratoire Chrono-Environnement, Université de Franche-Comté, 25211, Montbéliard Cedex, France
    • Metian, Marc. UMR CNRS 7266, Laboratoire Littoral Environnement et Sociétés, Université de La Rochelle, 17000, La Rochelle, France
    • Chatelain, Auriel. Laboratory of Soil Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland
    • Gilbert, Daniel. UMR CNRS/UFC 6249, Laboratoire Chrono-Environnement, Université de Franche-Comté, 25211, Montbéliard Cedex, France
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Microbial Ecology, 2013, vol. 66, no. 3, p. 571-580. Springer US; http://www.springer-ny.com
    Other Version
    Classification
    • Earth sciences
    OAI-PMH Identifier
    • oai:doc.rero.ch:316921
    Summary
    Although microorganisms are the primary drivers of biogeochemical cycles, the structure and functioning of microbial food webs are poorly studied. This is the case in Sphagnum peatlands, where microbial communities play a key role in the global carbon cycle. Here, we explored the structure of the microbial food web from a Sphagnum peatland by analyzing (1) the density and biomass of different microbial functional groups, (2) the natural stable isotope (δ 13C and δ 15N) signatures of key microbial consumers (testate amoebae), and (3) the digestive vacuole contents of Hyalosphenia papilio, the dominant testate amoeba species in our system. Our results showed that the feeding type of testate amoeba species (bacterivory, algivory, or both) translates into their trophic position as assessed by isotopic signatures. Our study further demonstrates, for H. papilio, the energetic benefits of mixotrophy when the density of its preferential prey is low. Overall, our results show that testate amoebae occupy different trophic levels within the microbial food web, depending on their feeding behavior, the density of their food resources, and their metabolism (i.e., mixotrophy vs. heterotrophy). Combined analyses of predation, community structure, and stable isotopes now allow the structure of microbial food webs to be more completely described, which should lead to improved models of microbial community function