title: High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors.
abstract: A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C), acetoclastic Methanosarcina (55 to 60°C) and hydrogenotrophic Methanothermobacter (60 to 65°C). The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Dang
authors.initials: D
authors.lastname: Ho
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Jensen
authors.affiliation: Centre for Marine BioInnovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Maria-Luisa
authors.initials: ML
authors.lastname: Gutierrez-Zamora
authors.affiliation: Centre for Marine BioInnovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Beckmann
authors.affiliation: Centre for Marine BioInnovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Mike
authors.initials: M
authors.lastname: Manefield
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Damien
authors.initials: D
authors.lastname: Batstone
mesh_terms: D000085:Acetates / Q000737:chemistry / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors; D002247:Carbon Isotopes; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D019605:Euryarchaeota / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D007553:Isotope Labeling; D007700:Kinetics; D008697:Methane / Q000096:biosynthesis*; D017020:Methanosarcina / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology; D013696:Temperature; D046968:Thermoanaerobacter / Q000145:classification / Q000235:genetics / Q000254:growth & development*
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D008697:Methane