Geomicrobiology and molecular biology of S- and Fe-oxidizing bacteria in subsurface sediments associated with the Yegua formation /
of sediment properties and groundwater geochemistry on microbial processes, and the community structure of bacteria were investigated in sediments of a Gulf Coast aquifer. Five portholes were drilled into the sands, silts, clays, and lignite of the Eocene Yegua formation in east-central Texas, and m...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=732837631&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | of sediment properties and groundwater geochemistry on microbial processes, and the community structure of bacteria were investigated in sediments of a Gulf Coast aquifer. Five portholes were drilled into the sands, silts, clays, and lignite of the Eocene Yegua formation in east-central Texas, and monitoring wells were installed in all water-bearing sands. Numbers of microorganisms ranged from [06] to [108] cells per gram dry weight [(gdw'1)], and viable amounts ranged from 0 to [106] cells [gdw'l]. Numbers of S- and Fe- oxidizing bacteria decreased with depth and ranged from 0 to 102 cells [gdw-l]. Low pH (3.8) and high sulfate (28 mM) and [Fe2+] (0.3 mM) contents argue for pyrite oxidation in shallow sediments. S- and Fe- oxidizing bacteria were readily detected in these sediments and likely play a role in pyrite oxidation. In consistent fashion, there was a relative paucity of pyrite in shallow sediments and a low [345/325] ratio (0.2%a), reflecting Contributions Sulfate from [34]s- depleted sulfides, in shallow regions. This pyrite oxidation potentially supplies sulfate to the deeper aquifers. PCR amplification of [16S] rDNA genes from sediment and water samples, using primer sets specific for the domain Bacteria and others specific for organisms of the genus Thiobacillus, yielded amplification that corresponded well with sediment geochemistry. Amplified DNA fragments of the V3 region of 16s rDNA were resolved by denaturing gradient gel electrophoresis (DGGE), and the resulting profiles were reproducible and specific for communities from different depths. Bacterial diversity estimated from the number and intensity of specific fragments in DGGE profiles decreased with depth. DNA amplified with primers specific for IL ferrooxidans and T. thiooxidans showed the presence of Z ferrooxidans to be most abundant above the oxidizing-to-reducing transition zone. Organisms isolated from the Yegua formation were phylogenetically most closely related to the species T ferrooxidans and 7: thiooxidans based on comparative molecular sequence (16s rDNA) analysis. Overall, sulfur cycling in shallow sediments and the transport of sulfate represents an important mechanism for commensal interaction among subsurface microorganisms by providing electron donors for chemoautotrophic bacteria and electron acceptors for heterotrophic bacteria. |
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| Item Description: | Vita. "Major Subject: Oceanography". |
| Physical Description: | x, 80 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references: pages 70-77. |