title: Connectivity to the surface determines diversity patterns in subsurface aquifers of the Fennoscandian shield.
abstract: Little research has been conducted on microbial diversity deep under the Earth's surface. In this study, the microbial communities of three deep terrestrial subsurface aquifers were investigated. Temporal community data over 6 years revealed that the phylogenetic structure and community dynamics were highly dependent on the degree of isolation from the earth surface biomes. The microbial community at the shallow site was the most dynamic and was dominated by the sulfur-oxidizing genera Sulfurovum or Sulfurimonas at all-time points. The microbial community in the meteoric water filled intermediate aquifer (water turnover approximately every 5 years) was less variable and was dominated by candidate phylum OD1. Metagenomic analysis of this water demonstrated the occurrence of key genes for nitrogen and carbon fixation, sulfate reduction, sulfide oxidation and fermentation. The deepest water mass (5000 year old waters) had the lowest taxon richness and surprisingly contained Cyanobacteria. The high relative abundance of phylogenetic groups associated with nitrogen and sulfur cycling, as well as fermentation implied that these processes were important in these systems. We conclude that the microbial community patterns appear to be shaped by the availability of energy and nutrient sources via connectivity to the surface or from deep geological processes.
authors.affiliation: Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Valerie
authors.initials: V
authors.lastname: Hubalek
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Alexander
authors.initials: A
authors.lastname: Eiler
authors.affiliation: Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Moritz
authors.initials: M
authors.lastname: Buck
authors.affiliation: Universität Göttingen, GZG -Geobiologie, Göttingen, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Heim
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
authors.forename: Mark
authors.initials: M
authors.lastname: Dopson
authors.affiliation: Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Stefan
authors.initials: S
authors.lastname: Bertilsson
authors.affiliation: Department of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Neuglobsow, Germany.
authors.forename: Danny
authors.identifier: 0000-0002-4658-8597
authors.initials: D
authors.lastname: Ionescu
mesh_terms: D044822:Biodiversity; D057486:Carbon Cycle; D020565:Epsilonproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D060587:Groundwater / Q000382:microbiology*; D056186:Metagenomics; D009584:Nitrogen / Q000378:metabolism; D010802:Phylogeny; D013455:Sulfur / Q000378:metabolism
chemical_list: D013455:Sulfur; D009584:Nitrogen