title: Chemolithotrophic primary production in a subglacial ecosystem.
abstract: Glacial comminution of bedrock generates fresh mineral surfaces capable of sustaining chemotrophic microbial communities under the dark conditions that pervade subglacial habitats. Geochemical and isotopic evidence suggests that pyrite oxidation is a dominant weathering process generating protons that drive mineral dissolution in many subglacial systems. Here, we provide evidence correlating pyrite oxidation with chemosynthetic primary productivity and carbonate dissolution in subglacial sediments sampled from Robertson Glacier (RG), Alberta, Canada. Quantification and sequencing of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) transcripts suggest that populations closely affiliated with Sideroxydans lithotrophicus, an iron sulfide-oxidizing autotrophic bacterium, are abundant constituents of microbial communities at RG. Microcosm experiments indicate sulfate production during biological assimilation of radiolabeled bicarbonate. Geochemical analyses of subglacial meltwater indicate that increases in sulfate levels are associated with increased calcite and dolomite dissolution. Collectively, these data suggest a role for biological pyrite oxidation in driving primary productivity and mineral dissolution in a subglacial environment and provide the first rate estimate for bicarbonate assimilation in these ecosystems. Evidence for lithotrophic primary production in this contemporary subglacial environment provides a plausible mechanism to explain how subglacial communities could be sustained in near-isolation from the atmosphere during glacial-interglacial cycles.
authors.affiliation: Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA The Wisconsin Astrobiology Research Consortium, University of Wisconsin, Madison, Wisconsin, USA eboyd@montana.edu.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Boyd
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA.
authors.forename: Trinity L
authors.initials: TL
authors.lastname: Hamilton
authors.affiliation: School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA.
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Havig
authors.affiliation: Department of Earth Sciences, Montana State University, Bozeman, Montana, USA.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Skidmore
authors.affiliation: School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, USA.
authors.forename: Everett L
authors.initials: EL
authors.lastname: Shock
mesh_terms: D000416:Alberta; D052818:Autotrophic Processes; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D017753:Ecosystem; D043372:Gallionellaceae / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D019015:Geologic Sediments / Q000382:microbiology*; D046448:Ice Cover / Q000382:microbiology; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism
chemical_list: D013431:Sulfates; D013440:Sulfides; C011342:pyrite; D007501:Iron; D012273:Ribulose-Bisphosphate Carboxylase
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