title: Low-temperature anaerobic digestion is associated with differential methanogenic protein expression.
abstract: Anaerobic digestion (AD) is an attractive wastewater treatment technology, leading to the generation of recoverable biofuel (methane). Most industrial AD applications, carry excessive heating costs, however, as AD reactors are commonly operated at mesophilic temperatures while handling waste streams discharged at ambient or cold temperatures. Consequently, low-temperature AD represents a cost-effective strategy for wastewater treatment. The comparative investigation of key microbial groups underpinning laboratory-scale AD bioreactors operated at 37, 15 and 7°C was carried out. Community structure was monitored using 16S rRNA clone libraries, while abundance of the most prominent methanogens was investigated using qPCR. In addition, metaproteomics was employed to access the microbial functions carried out in situ. While δ-Proteobacteria were prevalent at 37°C, their abundance decreased dramatically at lower temperatures with inverse trends observed for Bacteroidetes and Firmicutes. Methanobacteriales and Methanosaeta were predominant at all temperatures investigated while Methanomicrobiales abundance increased at 15°C compared to 37 and 7°C. Changes in operating temperature resulted in the differential expression of proteins involved in methanogenesis, which was found to occur in all bioreactors, as corroborated by bioreactors' performance. This study demonstrated the value of employing a polyphasic approach to address microbial community dynamics and highlighted the functional redundancy of AD microbiomes.
authors: Microbial Ecology Laboratory, School of Natural Sciences, National University of Ireland, Galway, University Road, Galway, Ireland Functional Environmental Microbiology, School of Natural Sciences, National University of Ireland, Galway, University Road, Galway, Ireland.
authors: Eoin
authors: E
authors: Gunnigle
authors: Microbial Ecology Laboratory, School of Natural Sciences, National University of Ireland, Galway, University Road, Galway, Ireland.
authors: Alma
authors: A
authors: Siggins
authors: BSRC Mass Spectrometry and Proteomics Facility, Biomedical Sciences Research Complex, North Haugh, University of St Andrews, Fife KY16 9ST, Scotland.
authors: Catherine H
authors: CH
authors: Botting
authors: BSRC Mass Spectrometry and Proteomics Facility, Biomedical Sciences Research Complex, North Haugh, University of St Andrews, Fife KY16 9ST, Scotland.
authors: Matthew
authors: M
authors: Fuszard
authors: Microbial Ecology Laboratory, School of Natural Sciences, National University of Ireland, Galway, University Road, Galway, Ireland.
authors: Vincent
authors: V
authors: O'Flaherty
authors: Functional Environmental Microbiology, School of Natural Sciences, National University of Ireland, Galway, University Road, Galway, Ireland florence.abram@nuigalway.ie.
authors: Florence
authors: F
authors: Abram
mesh_terms: D000693:Anaerobiosis; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D041963:Bacteroidetes / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D056804:Biofuels; D019149:Bioreactors; D003080:Cold Temperature; D020564:Deltaproteobacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D019605:Euryarchaeota / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D000068536:Bacillota / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D017012:Methanobacteriales / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D019640:Methanosarcinales / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D059013:Microbial Consortia; D040901:Proteomics / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D062065:Wastewater / Q000382:microbiology*
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D056804:Biofuels; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D062065:Wastewater
keywords: anaerobic digestion; low temperature; metaproteomics; methanogenic community; microbial phylogenetic diversity