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UBC Theses and Dissertations

Evaluating microbial community responses to blended biofuel contamination Arnold, Ashley Celine


As biofuel production increases, so too has the likelihood of accidental spills into the environment with important implications for human health and ecosystem functions. Such impacts can be evaluated at the microbial level as microorganisms are fundamental units of metabolism integral to the conversion of hydrocarbon substrates in the environment. Using the small subunit ribosomal (SSU or 16S) rRNA gene, we evaluate microbial community responses to ethanol and methanol blended biofuel contamination in terrestrial environments, through laboratory and field experiments, by assessing both community abundance and potential activity. For ethanol-based biofuel contamination, we observe differential patterns of enrichment in microbial taxa with traits relating to hydrocarbon degradation and fermentation across both field and laboratory experiments as well as changes in the abundance and potential activity of canonical methanogens. Observed differences highlight the role of the physical environment and the availability of organic matter in shaping microbial response patterns. Similar results were obtained for the methanol laboratory experiments, with respect hydrocarbon-degrading and fermentative taxa. However, a stronger methanogen response was observed suggesting that methanol blended fuels are more readily converted to methane under low organic loading conditions. Together, this work provides an initial assessment on the impact blended biofuels has on microbial community structure by identifying microbial taxa most responsive to contamination with implications for the development of remediation and risk assessment strategies.

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