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An Endolithic Microbial Community in Dolomite Rock in Central Switzerland: Characterization by Reflection Spectroscopy, Pigment Analyses, Scanning Electron Microscopy, and Laser Scanning Microscopy

Horath, T. ; Neu, T. ; Bachofen, R.

In: Microbial Ecology, 2006, vol. 51, no. 3, p. 353-364

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    Titre
    • An Endolithic Microbial Community in Dolomite Rock in Central Switzerland: Characterization by Reflection Spectroscopy, Pigment Analyses, Scanning Electron Microscopy, and Laser Scanning Microscopy
    Auteur
    • Horath, T.. Institute of Plant Biology/Microbiology, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
    • Neu, T.. Department of River Ecology, UFZ Center for Environmental Research, Leipzig-Halle, Brückstrasse 3A, D-39114, Magdeburg, Germany
    • Bachofen, R.. Institute of Plant Biology/Microbiology, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
    Type de document
    • Postprint
    Classification
    • Sciences de la terre
    Identifiant OAI-PMH
    • oai:doc.rero.ch:319372
    Summary
    A community of endolithic microorganisms dominated by phototrophs was found as a distinct band a few millimeters below the surface of bare exposed dolomite rocks in the Piora Valley in the Alps. Using in situ reflectance spectroscopy, we detected chlorophyll a (Chl a), phycobilins, carotenoids, and an unknown type of bacteriochlorophyll-like pigment absorbing in vivo at about 720nm. In cross sections, the data indicated a defined distribution of different groups of organisms perpendicular to the rock surface. High-performance liquid chromatography analyses of pigments extracted with organic solvents confirmed the presence of two types of bacteriochlorophylls besides chlorophylls and various carotenoids. Spherical organisms of varying sizes and small filaments were observed in situ with scanning electron microscopy and confocal laser scanning microscopy (one- and two-photon technique). The latter allowed visualization of the distribution of phototrophic microorganisms by the autofluorescence of their pigments within the rock. Coccoid cyanobacteria of various sizes predominated over filamentous ones. Application of fluorescence-labeled lectins demonstrated that most cyanobacteria were embedded in an exopolymeric matrix. Nucleic acid stains revealed a wide distribution of small heterotrophs. Some biological structures emitting a green autofluorescence remain to be identified