title: Microbial community structure in lake and wetland sediments from a high Arctic polar desert revealed by targeted transcriptomics.
abstract: While microbial communities play a key role in the geochemical cycling of nutrients and contaminants in anaerobic freshwater sediments, their structure and activity in polar desert ecosystems are still poorly understood, both across heterogeneous freshwater environments such as lakes and wetlands, and across sediment depths. To address this question, we performed targeted environmental transcriptomics analyses and characterized microbial diversity across three depths from sediment cores collected in a lake and a wetland, located on Cornwallis Island, NU, Canada. Microbial communities were characterized based on 16S rRNA and two functional gene transcripts: mcrA, involved in archaeal methane cycling and glnA, a bacterial housekeeping gene implicated in nitrogen metabolism. We show that methane cycling and overall bacterial metabolic activity are the highest at the surface of lake sediments but deeper within wetland sediments. Bacterial communities are highly diverse and structured as a function of both environment and depth, being more diverse in the wetland and near the surface. Archaea are mostly methanogens, structured by environment and more diverse in the wetland. McrA transcript analyses show that active methane cycling in the lake and wetland corresponds to distinct communities with a higher potential for methane cycling in the wetland. Methanosarcina spp., Methanosaeta spp. and a group of uncultured Archaea are the dominant methanogens in the wetland while Methanoregula spp. predominate in the lake.
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Magdalena K
authors.initials: MK
authors.lastname: Stoeva
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Mathematics and Statistics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Aris-Brosou
authors.affiliation: Environment Canada, National Wildlife Research Centre, Ottawa, Ontario, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Chételat
authors.affiliation: Department of Chemistry, Trent University, Peterborough, Ontario, Canada.
authors.forename: Holger
authors.initials: H
authors.lastname: Hintelmann
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Philip
authors.initials: P
authors.lastname: Pelletier
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Alexandre J
authors.initials: AJ
authors.lastname: Poulain
mesh_terms: D001110:Arctic Regions; D001483:Base Sequence; D044822:Biodiversity; D017931:DNA Primers; D017753:Ecosystem; D019015:Geologic Sediments / Q000382:microbiology*; D060106:Lakes; D016133:Polymerase Chain Reaction; D059467:Transcriptome; D014871:Water Microbiology; D053833:Wetlands
chemical_list: D017931:DNA Primers