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CHARACTERIZATION OF BACTERIAL COMMUNITIES OF RIVERBANK SEDIMENTS CONTAMINATED WITH POLYCYCLIC AROMATIC HYDROCARBONS

Johnston, Gloria P
http://rave.ohiolink.edu/etdc/view?acc_num=kent1397761347

Abstract Details

2014, PHD, Kent State University, College of Arts and Sciences / Department of Biological Sciences.
JOHNSTON, GLORIA P., Ph.D., May 2014 BIOLOGICAL SCIENCES CHARACTERIZATION OF BACTERIAL COMMUNITIES OF RIVERBANK SEDIMENTS CONTAMINATED WITH POLYCYCLIC AROMATIC HYDROCARBONS (213 PP) Director of Thesis: Laura G. Leff Microbial community structure and function are important to ecological processes and to the surrounding physical and chemical environment. Microbes also respond to changes in environmental conditions by oxidizing and transforming pollutants. Sediment contamination is a worldwide problem, yet there is a gap of information about geochemistry and structure of microbial communities in riverbank sediments impacted by long-term pollution. Characterizing the bacterial community in contaminated sediments is critical because it might reveal that some species have adapted to pollution and others can use the xenobiotic as energy and/or carbon sources. We measured high concentrations of polycyclic aromatic hydrocarbons (PAH) in riverbank sediments of the Mahoning River (Ohio, USA) derived from both pyrolytic and petrogenic sources, ranking this sediment as one of the most polluted aquatic ecosystems worldwide. A very high ecological risk to aquatic organisms, even at what was previously considered an unpolluted site was found. Multivariate statistics revealed that bacterial communities followed a temporal and spatial pattern similarly to that found in uncontaminated aquatic environments. PAHs, metals, sulfate, pH, and moisture represented a strong geochemical gradient that likely influenced community composition. Phylogenetic analysis of the 16S rDNA gene revealed groups of bacteria including d-proteobacteria, firmicutes, and bacteriodetes. Some members of these groups have been described as important in PAH degradation. Analysis of the dsrAB gene revealed that most sequences were closely affiliated with unknown, uncultured sulfate reducing bacteria (SRB). Two PAHs were used as models to measure their disappearance over time under sulfate reducing conditions and when a humic acid analogue (anthraquinone-2,6-disulfonate [AQDS]) was added to sediments. After 40-days of anaerobic incubation phenanthrene and fluorene degradation with AQDS was greatly increased in comparison to sediments undergoing natural attenuation. The presence of PAH-degrading and SRB indicated that degradation was likely a biotic mediated process. My research demonstrated that bacterial communities respond to intensive and extensive pollution and are driven by environmental conditions to different extents. In response, microbial communities likely used sulfate and humics for energy and PAHs as carbon sources, contributing to biogeochemical cycling of sulfur and carbon, and providing an important ecosystem function translated as degradation of PAHs.
Laura Leff (Advisor)
Andrea Case (Committee Member)
Xiaozhen Mou (Committee Member)
Isam Amin (Committee Member)
Joseph Ortiz (Committee Member)
213 p.
Biogeochemistry; Ecology; Environmental Science
bacterial communities, geochemistry, PAHs, sediments, sulfate reducing bacteria, biodegradation

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Citations

  • Johnston, G. P. (2014). CHARACTERIZATION OF BACTERIAL COMMUNITIES OF RIVERBANK SEDIMENTS CONTAMINATED WITH POLYCYCLIC AROMATIC HYDROCARBONS [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1397761347

    APA Style (7th edition)

  • Johnston, Gloria. CHARACTERIZATION OF BACTERIAL COMMUNITIES OF RIVERBANK SEDIMENTS CONTAMINATED WITH POLYCYCLIC AROMATIC HYDROCARBONS. 2014. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1397761347.

    MLA Style (8th edition)

  • Johnston, Gloria. "CHARACTERIZATION OF BACTERIAL COMMUNITIES OF RIVERBANK SEDIMENTS CONTAMINATED WITH POLYCYCLIC AROMATIC HYDROCARBONS." Doctoral dissertation, Kent State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1397761347

    Chicago Manual of Style (17th edition)

kent1397761347
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© 2014, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.