title: Microbial diversity in European alpine permafrost and active layers.
abstract: Permafrost represents a largely understudied genetic resource. Thawing of permafrost with global warming will not only promote microbial carbon turnover with direct feedback on greenhouse gases, but also unlock an unknown microbial diversity. Pioneering metagenomic efforts have shed light on the permafrost microbiome in polar regions, but temperate mountain permafrost is largely understudied. We applied a unique experimental design coupled to high-throughput sequencing of ribosomal markers to characterize the microbiota at the long-term alpine permafrost study site 'Muot-da-Barba-Peider' in eastern Switzerland with an approximate radiocarbon age of 12 000 years. Compared to the active layers, the permafrost community was more diverse and enriched with members of the superphylum Patescibacteria (OD1, TM7, GN02 and OP11). These understudied phyla with no cultured representatives proposedly feature small streamlined genomes with reduced metabolic capabilities, adaptations to anaerobic fermentative metabolisms and potential ectosymbiotic lifestyles. The permafrost microbiota was also enriched with yeasts and lichenized fungi known to harbour various structural and functional adaptation mechanisms to survive under extreme sub-zero conditions. These data yield an unprecedented view on microbial life in temperate mountain permafrost, which is increasingly important for understanding the biological dynamics of permafrost in order to anticipate potential ecological trajectories in a warming world.
authors.affiliation: Forest Soils and Biogeochemistry, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland.
authors.forename: Beat
authors.initials: B
authors.lastname: Frey
authors.affiliation: Forest Soils and Biogeochemistry, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rime
authors.affiliation: Snow and Permafrost, WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland.
authors.forename: Marcia
authors.initials: M
authors.lastname: Phillips
authors.affiliation: Forest Soils and Biogeochemistry, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland.
authors.forename: Beat
authors.initials: B
authors.lastname: Stierli
authors.affiliation: Laboratory of Ion Beam Physics, Swiss Federal Institute of Technology ETH Zurich, Zurich, Switzerland.
authors.forename: Irka
authors.initials: I
authors.lastname: Hajdas
authors.affiliation: Institute for Sustainability Sciences, Agroscope, Zurich, Switzerland.
authors.forename: Franco
authors.initials: F
authors.lastname: Widmer
authors.affiliation: Forest Soils and Biogeochemistry, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland martin.hartmann@wsl.ch.
authors.forename: Martin
authors.initials: M
authors.lastname: Hartmann
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D044822:Biodiversity; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D056186:Metagenomics; D065946:Permafrost / Q000737:chemistry / Q000382:microbiology*; D012988:Soil Microbiology; D013557:Switzerland
chemical_list: D002244:Carbon
keywords: Illumina Miseq sequencing; alpine permafrost; archaea; bacteria; eukarya; novel microbial diversity; ribosomal markers