title: Ecophysiology of an uncultivated lineage of Aigarchaeota from an oxic, hot spring filamentous 'streamer' community.
abstract: The candidate archaeal phylum 'Aigarchaeota' contains microorganisms from terrestrial and subsurface geothermal ecosystems. The phylogeny and metabolic potential of Aigarchaeota has been deduced from several recent single-cell amplified genomes; however, a detailed description of their metabolic potential and in situ transcriptional activity is absent. Here, we report a comprehensive metatranscriptome-based reconstruction of the in situ metabolism of Aigarchaeota in an oxic, hot spring filamentous 'streamer' community. Fluorescence in situ hybridization showed that these newly discovered Aigarchaeota are filamentous, which is consistent with the presence and transcription of an actin-encoding gene. Aigarchaeota filaments are intricately associated with other community members, which include both bacteria (for example, filamentous Thermocrinis spp.) and archaea. Metabolic reconstruction of genomic and metatranscriptomic data suggests that this aigarchaeon is an aerobic, chemoorganoheterotroph with autotrophic potential. A heme copper oxidase complex was identified in the environmental genome assembly and highly transcribed in situ. Potential electron donors include acetate, fatty acids, amino acids, sugars and aromatic compounds, which may originate from extracellular polymeric substances produced by other microorganisms shown to exist in close proximity and/or autochthonous dissolved organic carbon (OC). Transcripts related to genes specific to each of these potential electron donors were identified, indicating that this aigarchaeon likely utilizes several OC substrates. Characterized members of this lineage cannot synthesize heme, and other cofactors and vitamins de novo, which suggests auxotrophy. We propose the name Candidatus 'Calditenuis aerorheumensis' for this aigarchaeon, which describes its filamentous morphology and its primary electron acceptor, oxygen.
authors.affiliation: Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Beam
authors.affiliation: Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.
authors.forename: Zackary J
authors.initials: ZJ
authors.lastname: Jay
authors.affiliation: Divison of Microbial Ecology, University of Vienna, Vienna, Austria.
authors.forename: Markus C
authors.initials: MC
authors.lastname: Schmid
authors.affiliation: Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, USA.
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Rusch
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA, USA.
authors.forename: Margaret F
authors.initials: MF
authors.lastname: Romine
authors.affiliation: Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.
authors.forename: Ryan de M
authors.initials: Rde M
authors.lastname: Jennings
authors.affiliation: Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.|Sustainable Bioproducts LLC, Bozeman, MT, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kozubal
authors.affiliation: Department of Energy-Joint Genome Institute, Walnut Creek, CA, USA.
authors.forename: Susannah G
authors.identifier: http://orcid.org/0000-0001-6479-8427
authors.initials: SG
authors.lastname: Tringe
authors.affiliation: Divison of Microbial Ecology, University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.identifier: http://orcid.org/0000-0002-9778-7684
authors.initials: M
authors.lastname: Wagner
authors.affiliation: Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.|Pacific Northwest National Laboratory, Richland, WA, USA.
authors.forename: William P
authors.initials: WP
authors.lastname: Inskeep
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D017753:Ecosystem; D020745:Genome, Archaeal; D045482:Hot Springs / Q000032:analysis / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D056186:Metagenomics; D008969:Molecular Sequence Data; D010802:Phylogeny