title: Heterotrophic and autotrophic microbial populations in cold perennial springs of the high arctic.
abstract: The saline springs of Gypsum Hill in the Canadian high Arctic are a rare example of cold springs originating from deep groundwater and rising to the surface through thick permafrost. The heterotrophic bacteria and autotrophic sulfur-oxidizing bacteria (up to 40% of the total microbial community) isolated from the spring waters and sediments were classified into four phyla (Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria) based on 16S rRNA gene analysis; heterotrophic isolates were primarily psychrotolerant, salt-tolerant, facultative anaerobes. Some of the isolates contained genes for thiosulfate oxidation (soxB) and anoxygenic photosynthesis (pufM), possibly enabling the strains to better compete in these sulfur-rich environments subject to long periods of illumination in the Arctic summer. Although leucine uptake by the spring water microbial community was low, CO(2) uptake was relatively high under dark incubation, reinforcing the idea that primary production by chemoautotrophs is an important process in the springs. The small amounts of hydrocarbons in gases exsolving from the springs (0.38 to 0.51% CH(4)) were compositionally and isotopically consistent with microbial methanogenesis and possible methanotrophy. Anaerobic heterotrophic sulfur oxidation and aerobic autotrophic sulfur oxidation activities were demonstrated in sediment slurries. Overall, our results describe an active microbial community capable of sustainability in an extreme environment that experiences prolonged periods of continuous light or darkness, low temperatures, and moderate salinity, where life seems to rely on chemolithoautotrophy.
authors.affiliation: Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, QC H9X 3V9, Canada.
authors.forename: Nancy N
authors.initials: NN
authors.lastname: Perreault
authors.forename: Charles W
authors.initials: CW
authors.lastname: Greer
authors.forename: Dale T
authors.initials: DT
authors.lastname: Andersen
authors.forename: Stefanie
authors.initials: S
authors.lastname: Tille
authors.forename: Georges
authors.initials: G
authors.lastname: Lacrampe-Couloume
authors.forename: Barbara Sherwood
authors.initials: BS
authors.lastname: Lollar
authors.forename: Lyle G
authors.initials: LG
authors.lastname: Whyte
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000693:Anaerobiosis; D001110:Arctic Regions; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D002170:Canada; D002245:Carbon Dioxide / Q000378:metabolism; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D008697:Methane / Q000378:metabolism; D008969:Molecular Sequence Data; D010788:Photosynthesis; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013455:Sulfur / Q000378:metabolism; D013885:Thiosulfates / Q000378:metabolism; D014871:Water Microbiology
chemical_list: D000596:Amino Acids; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D013885:Thiosulfates; D002245:Carbon Dioxide; D013455:Sulfur; D008697:Methane