A contemporary microbially maintained subglacial ferrous "ocean".
An active microbial assemblage cycles sulfur in a sulfate-rich, ancient marine brine beneath Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, with Fe(III) serving as the terminal electron acceptor. Isotopic measurements of sulfate, water, carbonate, and ferrous iron and functional gene analyses of adenosine 5'-phosphosulfate reductase imply that a microbial consortium facilitates a catalytic sulfur cycle. These metabolic pathways result from a limited organic carbon supply because of the absence of contemporary photosynthesis, yielding a subglacial ferrous brine that is anoxic but not sulfidic. Coupled biogeochemical processes below the glacier enable subglacial microbes to grow in extended isolation, demonstrating how analogous organic-starved systems, such as Neoproterozoic oceans, accumulated Fe(II) despite the presence of an active sulfur cycle.
Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138 USA. jill.a.mikucki@dartmouth.edu
Jill A
JA
Mikucki
Ann
A
Pearson
David T
DT
Johnston
Alexandra V
AV
Turchyn
James
J
Farquhar
Daniel P
DP
Schrag
Ariel D
AD
Anbar
John C
JC
Priscu
Peter A
PA
Lee
D000693:Anaerobiosis; D000864:Antarctic Regions; D052818:Autotrophic Processes; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D017753:Ecosystem; D005290:Ferric Compounds / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism*; D052836:Heterotrophic Processes; D046448:Ice Cover; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010103:Oxygen Isotopes / Q000032:analysis; D010802:Phylogeny; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism; D013447:Sulfites / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*
D005290:Ferric Compounds; D005296:Ferrous Compounds; D010103:Oxygen Isotopes; D013431:Sulfates; D013447:Sulfites; D013455:Sulfur; D050862:Oxidoreductases Acting on Sulfur Group Donors; C019618:adenylylsulfate reductase; D010100:Oxygen