Aims: Methanogenesis is the terminal step in anaerobic digestion and is often rate-limiting and
highly sensitive to environmental changes. The performance of engineered anaerobic digesters
depends on methanogenesis, which is often measured indirectly through methane production and
COD removal. Quantitative real-time PCR (qPCR) is a culture-independent technique that can be
used to quantify populations of methanogenic archaea in anaerobic systems to provide insight into
system performance and community dynamics. The aims of this paper is to use a SYBR Greenbased
qPCR method to quantify methanogenic archaea in a variety of anaerobic digesters as a
prerequisite for long-term monitoring.
Methodology: In this study, genomic DNA was extracted from mixed liquor samples from five
anaerobic digesters using MO BIO Powersoil DNA Isolation kits. Primers targeted the 16S rRNA
Original Research Article
Hufnagel et al.; JABB, 4(2): 1-9, 2015; Article no.JABB.18655
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gene of different methanogens at the order- and family-level for qPCR using SYBR Green.
Comparisons were made between methanogen communities from different bioreactor conditions.
Results: Quantification of methanogens showed hydrogenotrophic dominance
(Methanobacteriales and Methanomicrobiales) in all bioreactors treating complex feed despite the
general assumption that 70% of methane is produced by acetotrophic methanogens. Furthermore,
the acetotrophic dominance found in the acetic acid-fed bioreactor showed an anticipated shift in
dominance from Methanosarcinaceae to Methanosaetacea when acetate concentrations
decreased.
Conclusions: This study illustrated that qPCR using SYBR Green can be used to quantify the
distribution of methanogens in anaerobic bioreactors at the order and family level. Methanogen
populations for these bioreactors were presented as well as recommendations for future
implementation.