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dc.contributor.authorGofstein, Taylor R.
dc.date.accessioned2021-10-20T20:16:49Z
dc.date.available2021-10-20T20:16:49Z
dc.date.issued2020-08
dc.identifier.urihttp://hdl.handle.net/11122/12295
dc.descriptionDissertation (Ph.D.) University of Alaska Fairbanks, 2020en_US
dc.description.abstractWith increased oil exploration, development, and transport in the Arctic in recent years, the potential for disastrous oil spills is imminent. Biodegradation, the consumption of contaminants by indigenous microorganisms capable of using them as an energy source, can be enhanced using bioremediation treatments and may be a viable spill remediation method when traditional physical recovery techniques are not. The EPA National Contingency Plan (NCP) product schedule lists oil spill response treatments that can be used in the event of a spill, many of which can stimulate intrinsic biodegradation. However, there is often little to no experimental data demonstrating the effectiveness of these products in aiding the remediation of a spill. Here we investigate the effects of the currently listed NCP products Corexit 9500 and Oil Spill Eater II (OSEII) on crude oil biodegradation in Arctic seawater and the associated shifts in the microbial community using mesocosm incubations. Despite conflicting reports in the literature, Corexit 9500 showed no inhibitory effects on the biodegradation of crude oil. When oil and Corexit were co-present, chemical and microbial data revealed a sequential degradation beginning with the non-ionic surfactant components of Corexit (Span 80, Tween 80, Tween 85), followed by the degradation of the labile alkane oil components, with the degradation of other Corexit components such as dioctyl sodium sulfosuccinate (DOSS) and dipropylene glycol n-butyl ether (DGBE) less clear. 16S rRNA gene sequencing revealed that oil and Corexit stimulate different microbial communities but some taxa are stimulated by either (Oleispira, Pseudofulvibacter, Roseobacter), suggesting that these organisms may be capable of degrading both. Further analysis with metatranscriptomic sequencing showed increased gene expression in the presence of Corexit, even when co-present with oil, suggesting that Corexit may enhance the metabolic activity of oil degraders. Increased expression of β-oxidation pathway genes (fadE, fadA, fadB) in the presence of Corexit coincided with the chemical loss of Corexit components. Based on these findings and the abundance of ester groups in the chemical structures of Corexit 9500 surfactant components, we propose a biodegradation pathway that involves the transformation of ester groups into fatty acids either through biotic lipase enzymes or abiotic hydrolysis, before funneling into the β-oxidation fatty acid degradation pathway. Taxonomic origins for these transcripts showed a diverse number of genera expressing these genes, which along with its lability may serve to explain the number of taxa observed to respond to Corexit both here and in the literature. Characterization of the contents of OSEII revealed the presence of sugars, surfactants, nutrients, phytochemicals, amylase, protease, and the non-hydrocarbonoclastic non-viable microorganisms Lactobacillus and Saccharomyces. Incubation experiments targeting the efficacy of OSEII showed a slight enhancement of n-alkane loss at 30 days, suggesting that it may have utility in longer term use following a post-spill nutrient depletion. However, the nutrient contents of OSEII were up to 32-fold times higher for ammonia and 100,000-fold times higher for iron than in ambient Arctic seawater, which although are limiting nutrients in seawater, may also cause more harmful ecological effects following a spill by inducing phytoplankton blooms. Based on these findings, the non-ionic surfactants of Corexit 9500 appear to be easily degraded through the proposed β-oxidation fatty acid pathway. Future NCP dispersants should target these labile ester chemical moieties while also being effective at dispersion. It is imperative for NCP products to undergo more rigorous third-party experiments to demonstrate their suitability, effectiveness, toxicity, and unintended side effects that may occur in situ before an oil spill occurs. Doing so will allow decision-makers to have comprehensive information to aid in selection of appropriate oil spill response techniques.en_US
dc.description.sponsorshipPrince William Sound Oil Spill Recovery Institute (PWS OSRI), Coastal Marine Institute (CMI), Biomedical Learning and Student Training (BLaST) program, Department of Defense National Defense Science and Engineering Graduate (DoD NDSEG) fellowshipen_US
dc.description.tableofcontentsChapter 1: General introduction -- Chapter 2: Sequential biodegradation of crude oil and Corexit EC9500A components in Arctic seawater -- Chapter 3: Metatranscriptomic shifts suggest shared biodegradation pathways for Corexit 9500 components and crude oil in Arctic seawater -- Chapter 4: Characterization of the commercial bioremediation product oil pill Eater II and its effects on crude oil biodegradation in Arctic seawater -- Chapter 5: General conclusion.en_US
dc.language.isoen_USen_US
dc.subjectPetroleumen_US
dc.subjectBiodegradationen_US
dc.subjectArctic Oceanen_US
dc.subjectBioremediationen_US
dc.subjectMarine bioremediationen_US
dc.subject.otherDoctor of Philosophy in Environmental Chemistryen_US
dc.titleFate and effects of commercial crude oil bioremediation products in Arctic seawateren_US
dc.typeDissertationen_US
dc.type.degreephden_US
dc.identifier.departmentDepartment of Chemistry and Biochemistryen_US
dc.contributor.chairLeigh, Mary Beth
dc.contributor.committeeSimpson, William
dc.contributor.committeeGuerard, Jennifer
dc.contributor.committeeCollins, R. Eric


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