Biodegradation of Naphthenic Acids by Microorganisms Originating from Alberta's Oil Sands Surface Mining Operations
Date
2021-01
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Abstract
Billions of liters of tailings water are produced from oil sands surface mining operations each year. Reclamation of tailings ponds is now a legislated process that must occur within 10 years after the end of an oil sands mining operation. To reclaim these waste ponds back to a natural landscape, toxic compounds must first be removed, including naphthenic acids (NAs), which are the primary toxic components. I investigated the biodegradation ability of three different microbial culture sets - photosynthetic algal-bacterial communities, aerobic bacterial communities, and a nitrate-reducing bacterial community - for their ability to metabolize the two model NAs cyclohexanecarboxylic acid (CHCA) and 1-adamantanecarboxylic acid (1-ADCA). Using gas chromatography-mass spectrophotometry, DNA stable isotope probing, and 16S/18S rRNA gene sequencing techniques, the work in this thesis illustrates the metabolism and organisms responsible for the biodegradation of the model NAs studied. All three microbial culture sets successfully biodegraded CHCA, while the structurally more complex 1-ADCA could only be biodegraded by the algal-bacterial communities, suggesting the potential value of such consortia for treating NA in oil sands tailings ponds. The DNA stable isotope probing experiments revealed that of the algae, members of the family Scenedesmaceae and the class Trebouxiophyceae both contribute to the biodegradation of CHCA. Brevundimonas and Rhodococcus were the two primary genera found associated with the biodegradation of CHCA in the aerobic bacterial communities. Sequencing results revealed that the nitrate-reducing bacterial community was primarily composed of known sulfate-reducing microorganisms, an intriguing result that warrants additional study.
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oil sands tailings pond, biodegradation, naphthenic acid, algae, bacteria, cyclohexanecarboxylic acid, 1-adamantanecarboxylic acid, bioremediation
Citation
Paulssen, J. M. (2021). Biodegradation of Naphthenic Acids by Microorganisms Originating from Alberta's Oil Sands Surface Mining Operations (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.