BITÖK
Bayreuther Institut für Terrestrische Ökosystemforschung
  Home Printable form Search fulltext Seite in deutsch Uni-Bayreuth
|  | Organisation |  | Research Publications |

Publications


>> internal Site (SSL)

Search:



 

Horn, MA; Matthies, C; Küsel, K; Schramm, A; Drake, HL: Hydrogenotrophic Methanogenesis by Moderately Acid-Tolerant Methanogens of a Methane-Emitting Acidic Peat, Applied and Environmental Microbiology, 69, 74-83 (2003)
Abstract:
The emission of methane (1.3 mmol CH4 m-2 d-1), precursors of methanogenesis, and the methanogenic microorganisms of acidic bog peat (pH 4.4) from a moderately reduced forest site were investigated by in situ measurements, microcosm incubations, and cultivation methods, respectively. Bog peat produced CH4 (0.4-1.7 µmol g [soil dry wt.]-1 d-1) under anoxic conditions. At in situ pH, supplemental H2-CO2, ethanol, or 1-propanol increased CH4-production rates, while formate, acetate, propionate, or butyrate inhibited the production of CH4; methanol had no effect on the production of CH4. H2-dependent acetogenesis occurred in H2-CO2-supplemented bog peat only after extended incubation periods. Non-supplemented bog peat initially produced small amounts of H2 that were subsequently consumed. The accumulation of H2 was stimulated by ethanol, 1-propanol, or by inhibiting methanogenesis with bromoethanesulfonate, and the consumption of ethanol was inhibited by high amounts of H2, results that collectively indicated that ethanol- or 1-propanol-utilizing bacteria were trophically associated with H2-utilizing methanogens. 109 anaerobes and 107 hydrogenotrophic methanogens per g bog peat dry weight were enumerated with cultivation techniques. A stable methanogenic enrichment was obtained with an acidic, H2-CO2-supplemented, fatty acid-enriched defined medium. CH4-production rates by the enrichment were similar at pH 4.5 and pH 6.5, and acetate inhibited methanogenesis at pH 4.5 but not at pH 6.5. 27 different archaeal 16S rRNA gene sequences indicative of Methanobacteriaceae, Methanomicrobiales, and Methanosarcinaceae were retrieved from the highest CH4-positive serial dilutions of bog peat and methanogenic enrichments. 10 bacterial 16S rRNA gene sequences were also retrieved from the same dilutions and enrichments, and were indicative of bacteria that might be responsible for the production of H2 that could be used by hydrogenotrophic methanogens. These results indicated that, in this acidic bog peat, (i) H2 is an important substrate for acid-tolerant methanogens, (ii) interspecies hydrogen transfer is involved in the degradation of organic carbon, (iii) the accumulation of protonated volatile fatty acids inhibits methanogenesis, and (iv) methanogenesis might be due to the activities of methanogens that are phylogenetic members of the Methanobacteriaceae, Methanomicrobiales, and Methanosarcinaceae.
This site makes use of cookies More information