Characterization of the microbial community in a biogas reactor supplied with organic residues
FakultätenFakultät für Naturwissenschaften
A mesophilic, continually operating, agricultural biogas plant utilizing predominantly biowaste was analyzed with respect to the composition and diversity of the microbial community as well as the stability of the microbial community over time by molecular methods. Therefore, different clone libraries containing specific DNA fragments were constructed. The bacterial community was dominated by the phyla Bacteroidetes, Firmicutes and Chloroflexi, and was composed of the bacterial families Clostridiaceae, Caldilineaceae, and Porphyromonadaceae. Methylotrophic bacteria were detected by the functional gene mxaF. Remarkably, the genus Methylocaldum is in the literature described as methantroph. The methanogenic archaeal community was dominated by the genus Methanoculleus. The current study provides the first report of the detection of fungal 18S rDNA sequences in biogas reactor content. Genera such as Saccharomyces and Mucor could be described. DGGE was used to monitor the bacterial and archaeal 16S rDNA as well as the eukaryotic 18S rDNA composition and showed a stable microbial community over a 15-months period. Fluorescence microscopy analyses were done to determine the total cell count (1.46 (± 0.3)× 1010 cells ml-1) using stained cells and to detect methanogenic archaeal cells (3.5 (± 0.78)× 108 cells ml-1) using their native coenzyme F420 autofluorescence. Substrates such as biowaste possess low structure and provide a high energy potential if supplied to a biogas reactor. To stabilize a biogas-forming process at higher organic loading rates, straw was added to the biogas reactor to provide surfaces for microorganisms to form biofilms. With respect to the hypothesis, evidence was found for a higher abundance of a syntrophic bacterium, Candidatus Cloacamonas acidaminovorans, living in the biofilm on straw. It seems that this organism undergoes some kind of syntrophic interaction with the predominating hydrogenotrophic methanogenic archaea of the genus Methanocullus.
Erstellung / Fertigstellung
Normierte SchlagwörterBiogastechnik [GND]
Methylotrophe Bakterien [GND]
Methylotrophic bacteria [LCSH]