title: Microbial community redundancy in anaerobic digestion drives process recovery after salinity exposure.
abstract: Anaerobic digestion of high-salinity wastewaters often results in process inhibition due to the susceptibility of the methanogenic archaea. The ability of the microbial community to deal with increased salinity levels is of high importance to ensure process perseverance or recovery after failure. The exact strategy of the microbial community to ensure process endurance is, however, often unknown. In this study, we investigated how the microbial community is able to recover process performance following a disturbance through the application of high-salinity molasses wastewater. After a stable start-up, methane production quickly decreased from 625 ± 17 to 232 ± 35 mL CH4L-1d-1with a simultaneous accumulation in volatile fatty acids up to 20.5 ± 1.4 g COD L-1, indicating severe process disturbance. A shift in feedstock from molasses wastewater to waste activated sludge resulted in complete process recovery. However, the bacterial and archaeal communities did not return to their original composition as before the disturbance, despite similar process conditions. Microbial community diversity was recovered to similar levels as before disturbance, which indicates that the metabolic potential of the community was maintained. A mild increase in ammonia concentration after process recovery did not influence methane production, indicating a well-balanced microbial community. Hence, given the change in community composition following recovery after salinity disturbance, it can be assumed that microbial community redundancy was the major strategy to ensure the continuation of methane production, without loss of functionality or metabolic flexibility.
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium.
authors.forename: Jo
authors.initials: J
authors.lastname: De Vrieze
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium.
authors.forename: Marlies E R
authors.initials: MER
authors.lastname: Christiaens
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium.
authors.forename: Diego
authors.initials: D
authors.lastname: Walraedt
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium.
authors.forename: Arno
authors.initials: A
authors.lastname: Devooght
authors.affiliation: Infrastructure and Environment Research Division, School of Engineering, University of Glasgow, UK.
authors.forename: Umer Zeeshan
authors.initials: UZ
authors.lastname: Ijaz
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium. Electronic address: Nico.Boon@UGent.be.
authors.forename: Nico
authors.initials: N
authors.lastname: Boon
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology*; D008697:Methane / Q000378:metabolism; D054712:Salinity; D012722:Sewage / Q000382:microbiology
chemical_list: D012722:Sewage; D008697:Methane
keywords: 16S rRNA gene; Biogas; Illumina sequencing; Methanogenesis; Microbiome; Salt