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Use of an isothermal microcalorimetry assay to characterize microbial oxalotrophic activity

Bravo, Daniel ; Braissant, Olivier ; Solokhina, Anna ; Clerc, Martin ; Daniels, Alma U. ; Verrecchia, Eric ; Junier, Pilar

In: FEMS Microbiology Ecology, 2011, vol. 78, no. 2, p. 266-274

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    Title
    • Use of an isothermal microcalorimetry assay to characterize microbial oxalotrophic activity
    Author
    • Bravo, Daniel. Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
    • Braissant, Olivier. Laboratory of Biomechanics & Biocalorimetry (LOB2) Biozentrum/Pharmazentrum, University of Basel, Basel, Switzerland
    • Solokhina, Anna. Laboratory of Biomechanics & Biocalorimetry (LOB2) Biozentrum/Pharmazentrum, University of Basel, Basel, Switzerland
    • Clerc, Martin. Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
    • Daniels, Alma U.. Laboratory of Biomechanics & Biocalorimetry (LOB2) Biozentrum/Pharmazentrum, University of Basel, Basel, Switzerland
    • Verrecchia, Eric. Biogeoscience Laboratory, Institute of Geology and Paleontology, University of Lausanne, Lausanne, Switzerland
    • Junier, Pilar. Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:299438
    Summary
    Isothermal microcalorimetry (IMC) has been used in the past to monitor metabolic activities in living systems. A few studies have used it on ecological research. In this study, IMC was used to monitor oxalotrophic activity, a widespread bacterial metabolism found in the environment, and particularly in soils. Six model strains were inoculated in solid angle media with K-oxalate as the sole carbon source.Cupriavidus oxalaticus,Cupriavidus necator, andStreptomyces violaceoruber presented the highest activity (91, 40, and 55 μW, respectively) and a maximum growth rate (μmax h−1) of 0.264, 0.185, and 0.199, respectively, among the strains tested. These three strains were selected to test the incidence of different oxalate sources (Ca, Cu, and Fe-oxalate salts) in the metabolic activity. The highest activity was obtained in Ca-oxalate forC. oxalaticus. Similar experiments were carried out with a model soil to test whether this approach can be used to measure oxalotrophic activity in field samples. Although measuring oxalotrophic activity in a soil was challenging, there was a clear effect of the amendment with oxalate on the metabolic activity measured in soil. The correlation between heat flow and growth suggests that IMC analysis is a powerful method to monitor bacterial oxalotrophic activity