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Wüst, PK; Horn, MA; Drake, HL: Trophic Links between Fermenters and Methanogens in a Moderately Acidic Fen Soil, Environmental Microbiology, 11 (6), 1395-1409 (2009)
Trophic links between fermentation and methanogenesis of soil derived from a methane-emitting, moderately acidic temperate fen (pH 4.5) were investigated. Initial CO2:CH4 production ratios in anoxic microcosms indicated that methanogenesis was concomitant to other terminal anaerobic processes. Methane production in anoxic microcosms at in situ pH was stimulated by supplemental H2-CO2, formate, or methanol; supplemental acetate did not stimulate methanogenesis. Supplemental H2-CO2, formate, or methanol also stimulated the formation of acetate, indicating that the fen harbors moderately acid-tolerant acetogens. Supplemental monosaccharides (glucose, N-acetylglucosamine, and xylose) stimulated the production of CO2, H2, acetate, and other fermentation products when methanogenesis was inhibited with 2-bromoethane sulfonate (BES) (20 mM). Glucose stimulated methanogenesis in the absence of BES. Upper soil depths yielded higher anaerobic activities and also higher numbers of cells. Detected archaeal 16S rRNA genes were indicative of H2-CO2- and formate-consuming methanogens (Methanomicrobiaceae), obligate acetoclastic methanogens (Methanosaetaceae), and crenarchaeotes (groups I.1a, I.1c, and I.3). Molecular analyses of partial sequences of 16S rRNA genes revealed the presence of Acidobacteria, Nitrospirales, Clamydiales, Clostridiales, Alpha-, Gamma-, Delta-Proteobacteria, and Cyanobacteria. These collective results suggest that this moderately acidic fen harbors phylogenetically diverse, moderately acid tolerant fermenters (both facultative aerobes and obligate anaerobes) that are trophically linked to methanogenesis.

Letzte Änderung 07.07.2009