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dc.contributor.authorHamilton, T. L.
dc.contributor.authorWelander, P. V.
dc.contributor.authorAlbrecht, H. L.
dc.contributor.authorFulton, J. M.
dc.contributor.authorSchaperdoth, I.
dc.contributor.authorBird, L. R.
dc.contributor.authorFreeman, K. H.
dc.contributor.authorMacalady, J. L.
dc.contributor.authorSummons, Roger E
dc.date.accessioned2018-10-16T19:48:43Z
dc.date.available2018-10-16T19:48:43Z
dc.date.issued2017-10
dc.date.submitted2016-09
dc.identifier.issn1472-4677
dc.identifier.issn1472-4669
dc.identifier.urihttp://hdl.handle.net/1721.1/118593
dc.description.abstractLittle Salt Spring (Sarasota County, FL, USA) is a sinkhole with groundwater vents at ~77 m depth. The entire water column experiences sulfidic (~50 μM) conditions seasonally, resulting in a system poised between oxic and sulfidic conditions. Red pinnacle mats occupy the sediment–water interface in the sunlit upper basin of the sinkhole, and yielded 16S rRNA gene clones affiliated with Cyanobacteria, Chlorobi, and sulfate-reducing clades of Deltaproteobacteria. Nine bacteriochlorophyll e homologues and isorenieratene indicate contributions from Chlorobi, and abundant chlorophyll a and pheophytin a are consistent with the presence of Cyanobacteria. The red pinnacle mat contains hopanoids, including 2-methyl structures that have been interpreted as biomarkers for Cyanobacteria. A single sequence of hpnP, the gene required for methylation of hopanoids at the C-2 position, was recovered in both DNA and cDNA libraries from the red pinnacle mat. The hpnP sequence was most closely related to cyanobacterial hpnP sequences, implying that Cyanobacteria are a source of 2-methyl hopanoids present in the mat. The mats are capable of light-dependent primary productivity as evidenced by13C-bicarbonate photoassimilation. We also observed13C-bicarbonate photoassimilation in the presence of DCMU, an inhibitor of electron transfer to Photosystem II. Our results indicate that the mats carry out light-driven primary production in the absence of oxygen production—a mechanism that may have delayed the oxygenation of the Earth's oceans and atmosphere during the Proterozoic Eon. Furthermore, our observations of the production of 2-methyl hopanoids by Cyanobacteria under conditions of low oxygen and low light are consistent with the recovery of these structures from ancient black shales as well as their paucity in modern marine environments.en_US
dc.description.sponsorshipNational Science Foundation (U.S.) (Grant EAR‐0525503)en_US
dc.description.sponsorshipUnited States. National Aeronautics and Space Administration (Grant NNA04CC06A)en_US
dc.description.sponsorshipUnited States. National Aeronautics and Space Administration (Grant NNA13AA90A)en_US
dc.publisherWiley Blackwellen_US
dc.relation.isversionofhttp://dx.doi.org/10.1111/GBI.12252en_US
dc.rightsCreative Commons Attribution 4.0 International Licenseen_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en_US
dc.sourceWileyen_US
dc.titleMicrobial communities and organic biomarkers in a Proterozoic-analog sinkholeen_US
dc.typeArticleen_US
dc.identifier.citationHamilton, T. L. et al “Microbial Communities and Organic Biomarkers in a Proterozoic-Analog Sinkhole.” Geobiology 15, 6 (October 2017): 784–797 © 2017 The Authorsen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciencesen_US
dc.contributor.mitauthorSummons, Roger E
dc.relation.journalGeobiologyen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dc.date.updated2018-10-02T17:55:05Z
dspace.orderedauthorsHamilton, T. L.; Welander, P. V.; Albrecht, H. L.; Fulton, J. M.; Schaperdoth, I.; Bird, L. R.; Summons, R. E.; Freeman, K. H.; Macalady, J. L.en_US
dspace.embargo.termsNen_US
dc.identifier.orcidhttps://orcid.org/0000-0002-7144-8537
mit.licensePUBLISHER_CCen_US


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