Date of Award

12-2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Engineering and Science

Advisor

Finneran, Kevin T

Committee Member

Lee, Cindy

Committee Member

Saski, Christopher

Abstract

Understanding how fuel oxygenates interact with microorganisms in the subsurface is important for the remediation of contaminated sites and designing and optimizing remedial strategies. The current understanding of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA) degradation in the environment has been developed primarily through gas chromatography GC analysis and culture-based laboratory studies. Microbial communities can be very diverse, and while microcosm studies provide valuable data, few metagenomic studies have been performed. To elucidate the significant microorganisms and pathways involved in the breakdown of MTBE and TBA, the compositions of entire indigenous microbial populations must be investigated and compared. Biodegradation of MTBE and TBA have been observed under most redox conditions, but all anoxic degradation pathways are still unknown, and anaerobic pure cultures, capable of MTBE or TBA degradation, have not yet been isolated. Furthermore, the success of anoxic degradation varies between studies, suggesting site-specific conditions are of paramount importance. My work utilizes culture-independent sequencing methods to more inclusively examine the composition of entire microbial communities. Anaerobic biodegradation of MTBE and TBA contamination in the subsurface is not well understood. Natural attenuation of TBA in soil and groundwater has been observed at some sites, but TBA contamination persists at other sites. My study investigated the microbial ecology associated with sites where TBA degradation has been observed versus sites where TBA persists in the subsurface. Groundwater and soil core samples were obtained from various TBA-contaminated sites throughout the United States. The sites were categorized into two main groups: TBA-degrading and non-degrading. At some of the sites TBA degradation had been observed while TBA-contamination persisted at constant levels at the other sites, this was the basis for the classifications. DNA was extracted from anaerobic groundwater and soil core samples, PCR amplified, and sequenced using Illumina MiSeq high throughput sequencing technology. The resulting sequences were then analyzed, providing insight into microbial community composition present at various sites. My results highlight microbial groups that might be significant in anaerobic TBA biodegradation and warrant further investigation.

Included in

Engineering Commons

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