title: Genomic insights into members of the candidate phylum Hyd24-12 common in mesophilic anaerobic digesters.
abstract: Members of the candidate phylum Hyd24-12 are globally distributed, but no genomic information or knowledge about their morphology, physiology or ecology is available. In this study, members of the Hyd24-12 lineage were shown to be present and abundant in full-scale mesophilic anaerobic digesters at Danish wastewater treatment facilities. In some samples, a member of the Hyd24-12 lineage was one of the most abundant genus-level bacterial taxa, accounting for up to 8% of the bacterial biomass. Three closely related and near-complete genomes were retrieved using metagenome sequencing of full-scale anaerobic digesters. Genome annotation and metabolic reconstruction showed that they are Gram-negative bacteria likely involved in acidogenesis, producing acetate and hydrogen from fermentation of sugars, and may play a role in the cycling of sulphur in the digesters. Fluorescence in situ hybridization revealed single rod-shaped cells dispersed within the flocs. The genomic information forms a foundation for a more detailed understanding of their role in anaerobic digestion and provides the first insight into a hitherto undescribed branch in the tree of life.
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Rasmus Hansen
authors.initials: RH
authors.lastname: Kirkegaard
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Morten Simonsen
authors.identifier: 0000-0003-4135-2670
authors.initials: MS
authors.lastname: Dueholm
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Simon Jon
authors.identifier: 0000-0003-3749-8730
authors.initials: SJ
authors.lastname: McIlroy
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Marta
authors.initials: M
authors.lastname: Nierychlo
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Søren Michael
authors.initials: SM
authors.lastname: Karst
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Albertsen
authors.affiliation: Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
authors.forename: Per Halkjær
authors.initials: PH
authors.lastname: Nielsen
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology; D005285:Fermentation; D023281:Genomics; D017404:In Situ Hybridization, Fluorescence; D054892:Metagenome; D062065:Wastewater / Q000382:microbiology*
chemical_list: D062065:Wastewater