Title page for ETD etd-06042004-075312


Type of Document Master's Thesis
Author Rhodes, Rachelle Renee
URN etd-06042004-075312
Title Investigating the Functional Response of a Subsurface Biofilm Community to Xenobiotic Stress
Degree Master of Science
Department Environmental Engineering
Advisory Committee
Advisor Name Title
Love, Nancy G. Committee Chair
Novak, John T. Committee Member
Schreiber, Madeline E. Committee Member
Keywords
  • GGKE
  • Biofilm
  • functional response
  • potassium
Date of Defense 2004-05-12
Availability unrestricted
Abstract
ABSTRACT

Biologically-mediated subsurface remediation by biofilm communities is a poorly understood process that is spatially and temporally dynamic. Two microbial responses, catabolism and the stress response glutathione-gated potassium efflux (GGKE), to benzene, pentachlorophenol (PCP), or Cd exposure were studied in up-flow sand columns to examine the contribution of each response to the overall functional response of a subsurface biofilm. Benzene was catabolized in the aerobic zone, and did not activate the GGKE response, and exhibited the highest biomass concentrations of all columns. PCP was not catabolized during this study, but was found to elicit two responses, oxidative phosphorylation uncoupling and GGKE, that appeared to be concentration dependent. Oxidative uncoupling was the controlling metabolic response up to 10 mg/L PCP, while the GGKE stress response was activated near 20 mg/L PCP. PCP column biomass did not show long-term biomass detachment, although immediate detachment occurred during initial GGKE activation. Cd column biomass activated the GGKE response as perturbing Cd concentrations increased. Extracellular polymeric substance (EPS)-Cd complexation was a possible detoxification mechanism, as biomass concentrations did not decrease with increasing Cd concentration, and increased as Cd concentrations decreased. Results of this study suggested that the increased exposure of electrophilic contaminants to sand column biomass did not cause biomass detachment.

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  01Thesis.pdf 1.27 Mb 00:05:54 00:03:02 00:02:39 00:01:19 00:00:06
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