title: Microwave and ultrasound pre-treatments influence microbial community structure and digester performance in anaerobic digestion of waste activated sludge.
abstract: Comparative analyses of bacterial and archaeal community structures and dynamics in three biogas digesters during start-up and subsequent operation using microwaved, ultrasonicated or untreated waste activated sludge were performed based on 454 pyrosequencing datasets of part of 16S ribosomal RNA sequences and quantitative PCR. The pre-treatment increased the solubility, and thus the availability of the substrate for microbial degradation and significantly affected the succession of the anaerobic community structure over the course of the digestion. Bacteroidetes, Proteobacteria and Firmicutes were the dominant phyla in all digesters throughout operation. Proteobacteria decreased in relative abundance from 23-26 % to 11-13 % in association with enhanced substrate availability. Negative correlations between relative abundance of Alpha-, Beta- and Gammaproteobacteria and the substrate availability and/or biogas production were disclosed in statistical analyses. Clostridiales was the dominant order in Firmicutes, and Clostridiales, Clostridia and Firmicutes relative abundance and richness were shown to positively correlate with substrate availability and biogas generation. Methanogenic communities had a fairly restricted structure, highly dominated by Methanosaeta and Methanobrevibacter phylotypes. A gradual decline in Methanobrevibacter and increased representation of Methanosaeta concilii over time were particularly apparent in the digester receiving untreated waste activated sludge, whereas more diversified archaeal communities were maintained in the pre-treatment digesters. The quantitative PCR analyses revealed a methanogenic community distribution that coincided with the 454 pyrosequencing data.
authors.affiliation: Department of Chemical Engineering, Process and Environmental Technology Lab, KU Leuven, Technology Campus De Nayer, J. De Nayerlaan 5, B-2860, Sint-Katelijne-Waver, Belgium.
authors.forename: Maria
authors.initials: M
authors.lastname: Westerholm
authors.affiliation: Department of Microbial and Molecular Systems (M2S), Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), KU Leuven, Campus De Nayer, Fortsesteenweg 30A, B-2860, Sint-Katelijne-Waver, Belgium.
authors.forename: Sam
authors.initials: S
authors.lastname: Crauwels
authors.affiliation: Department of Biology, Plant Conservation and Population Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001, Heverlee, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Van Geel
authors.affiliation: Department of Chemical Engineering, Process and Environmental Technology Lab, KU Leuven, Technology Campus De Nayer, J. De Nayerlaan 5, B-2860, Sint-Katelijne-Waver, Belgium.
authors.forename: Raf
authors.initials: R
authors.lastname: Dewil
authors.affiliation: Department of Microbial and Molecular Systems (M2S), Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), KU Leuven, Campus De Nayer, Fortsesteenweg 30A, B-2860, Sint-Katelijne-Waver, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Lievens
authors.affiliation: Department of Chemical Engineering, Process and Environmental Technology Lab, KU Leuven, Technology Campus De Nayer, J. De Nayerlaan 5, B-2860, Sint-Katelijne-Waver, Belgium. lise.appels@cit.kuleuven.be.
authors.forename: Lise
authors.initials: L
authors.lastname: Appels
mesh_terms: D000693:Anaerobiosis / Q000502:physiology / Q000528:radiation effects; D001105:Archaea / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D041963:Bacteroidetes / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D056804:Biofuels; D019149:Bioreactors / Q000382:microbiology; D019605:Euryarchaeota / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D014644:Genetic Variation; D059014:High-Throughput Nucleotide Sequencing; D008697:Methane / Q000096:biosynthesis*; D059013:Microbial Consortia / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D008872:Microwaves; D020560:Proteobacteria / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D012336:RNA, Ribosomal, 16S; D060888:Real-Time Polymerase Chain Reaction; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D000069453:Ultrasonic Waves
chemical_list: D056804:Biofuels; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D008697:Methane
keywords: Biogas; Methanogenesis; Microbial dynamics and diversity; Next generation sequencing; Wastewater sludge; qPCR