Functional responses and adaptation of mesophilic microbial communities to psychrophilic anaerobic digestion.
Psychrophilic (<20°C) anaerobic digestion (AD) represents an attractive alternative to mesophilic wastewater treatment. In order to investigate the AD microbiome response to temperature change, with particular emphasis on methanogenic archaea, duplicate laboratory-scale AD bioreactors were operated at 37°C followed by a temperature drop to 15°C. A volatile fatty acid-based wastewater (composed of propionic acid, butyric acid, acetic acid and ethanol) was used to provide substrates representing the later stages of AD. Community structure was monitored using 16S rRNA gene clone libraries, as well as DNA and cDNA-based DGGE analysis, while the abundance of relevant methanogens was followed using qPCR. In addition, metaproteomics, microautoradiography-fluorescence in situ hybridization, and methanogenic activity measurements were employed to investigate microbial activities and functions. Methanomicrobiales abundance increased at low temperature, which correlated with an increased contribution of CH4 production from hydrogenotrophic methanogenesis at 15°C. Methanosarcinales utilized acetate and H2/CO2 as CH4 precursors at both temperatures and a partial shift from acetoclastic to hydrogenotrophic methanogenesis was observed for this archaeal population at 15°C. An upregulation of protein expression was reported at low temperature as well as the detection of chaperones indicating that mesophilic communities experienced stress during long-term exposure to 15°C. Overall, changes in microbial community structure and function were found to underpin the adaptation of mesophilic sludge to psychrophilic AD.
Microbial Ecology Laboratory, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland Functional Environmental Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
Eoin
E
Gunnigle
Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
Jeppe L
JL
Nielsen
Biomedical Sciences Research Complex, Biomolecular Sciences Building, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, UK.
Matthew
M
Fuszard
Biomedical Sciences Research Complex, Biomolecular Sciences Building, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, UK.
Catherine H
CH
Botting
School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, Ireland.
Jerome
J
Sheahan
Microbial Ecology Laboratory, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
Vincent
V
O'Flaherty
Functional Environmental Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland florence.abram@nuigalway.ie.
Florence
F
Abram
D000064:Acclimatization / Q000235:genetics / Q000502:physiology; D000693:Anaerobiosis / Q000502:physiology; D001483:Base Sequence; D019149:Bioreactors / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D008697:Methane / Q000096:biosynthesis / Q000378:metabolism; D017018:Methanomicrobiales / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D019640:Methanosarcinales / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D059013:Microbial Consortia; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017423:Sequence Analysis, RNA; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D018508:Water Purification / Q000379:methods*
D012336:RNA, Ribosomal, 16S; D012722:Sewage; D008697:Methane
MAR-FISH; anaerobic digestion; metaproteomics; methanogenesis; microbial phylogenetic diversity; psychrophilic