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dc.contributor.authorMills, Heath Jordanen_US
dc.date.accessioned2005-03-02T22:18:52Z
dc.date.available2005-03-02T22:18:52Z
dc.date.issued2004-07-08en_US
dc.identifier.urihttp://hdl.handle.net/1853/5022
dc.description.abstractA molecular phylogenetic approach was used to characterize the composition of microbial communities from two gas hydrate sedimentary systems in the Gulf of Mexico. Nucleic acids were extracted from three distinct locales on surface breaching gas hydrate mounds, i.e., sediment overlaying gas hydrate, sediment/hydrate interface and sediment-free hydrate, and from three sediment depths, i.e., 0-2, 6-8 and 10-12 cm, in Beggiatoa sp. mat-associated sediments located several meters from exposed gas hydrate. Samples were collected from a research submersible (water depth 550-575 m) during two research cruises aboard the R/V Seward Johnson I and II funded by the NSF Life in Extreme Environments program. The 16S rRNA gene and 16S rRNA were amplified using PCR and reverse transcription-PCR, respectively, from DNA and RNA extracted from the total microbial community. The primers targeted microorganisms at the domain-specific, i.e., Bacteria and Archaea, and group-specific, i.e., sulfate-reducing bacteria (SRB) and putative anaerobic methane-oxidizing (ANME) archaea, level. Sequence analysis of the Bacteria clones revealed that the microbial communities were primarily dominated by Deltaproteobacteria. Other Proteobacteria classes, including Epsilon- and Gammaproteobacteria, represented a large fraction of the total microbial community isolated from the sediment overlying hydrate sample and the metabolically active fraction of the 0-2 cm sediment depth sampled from the Beggiatoa sp. mat-associated sediments. Sequence analysis indicated the majority of the archaeal clones were most closely related to Methanosarcinales, Methanomicrobiales and distinct lineages within the ANME groups. Several novel lineages were identified including a fourth ANME-2 clade, i.e., ANME-2D, and three clades with no closely related previously sequenced 16S rRNA gene clones or isolates, i.e., Unclassified Bacteria groups 1 and 2 and Unclassified Euryarchaeota. These studies represent the first 16S rRNA gene and 16S rRNA phylogenetic-based description of microbial communities extant in sediment-free gas hydrate and in methane-rich hydrate-associated and Beggiatoa sp.-associated sediments from a hydrocarbon seep region in the Gulf of Mexico.en_US
dc.format.extent7195551 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectMicrobial diversityen_US
dc.subject16S
dc.subjectGulf of Mexico
dc.subjectCold seep
dc.subject.lcshGeochemistry Mexico, Gulf ofen_US
dc.subject.lcshMicrobial ecologyen_US
dc.titleMicrobial diversity in sediments and gas hydrates associated with cold seeps in the Gulf of Mexicoen_US
dc.typeDissertationen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentBiologyen_US
dc.description.advisorCommittee Chair: Patricia Sobecky; Committee Member: Frank Loeffler; Committee Member: Joseph Montoya; Committee Member: Roger Wartell; Committee Member: Thomas DiChristinaen_US


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