title: Investigation into the effect of high concentrations of volatile fatty acids in anaerobic digestion on methanogenic communities.
abstract: A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP. In addition, real-time PCR was used to quantify the presence of the different methanogenic genera in the sludge samples. Array results indicated that the archaeal communities in the different reactors were stable, and that changes in the VFA levels of the anaerobic digesters did not greatly alter the dominating methanogenic organisms. In contrast, the two digesters were found to harbour different dominating methanogenic communities, which appeared to remain stable over time. Real-time PCR results were inline with those of microarray analysis indicating only minimal changes in methanogen numbers during periods of high VFAs, however, revealed a greater diversity in methanogens than found with the array.
authors.affiliation: Institut für Mikrobiologie, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria. Electronic address: ingrid.whittle@uibk.ac.at.
authors.forename: Ingrid H
authors.initials: IH
authors.lastname: Franke-Whittle
authors.affiliation: Institut für Mikrobiologie, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Walter
authors.affiliation: Abwasserverband Zirl und Umgebung, Meilbrunnen 5, 6170 Zirl, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Ebner
authors.affiliation: Institut für Mikrobiologie, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
authors.forename: Heribert
authors.initials: H
authors.lastname: Insam
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000494:pharmacology*; D008697:Methane / Q000096:biosynthesis; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D005232:Fatty Acids, Volatile; D012336:RNA, Ribosomal, 16S; D008697:Methane
keywords: ANAEROCHIP; Anaerobic digestion (AD); Methanogens; Real-time PCR; Volatile fatty acids (VFAs)