Characterization of extremophilic sulfur oxidizing microbial communities inhabiting the sulfur blocks of Alberta's oil sands
This study was designed to determine if Alberta's sulfur blocks were inhabited by microorganisms which contribute to oxidation of elemental sulfur. The first objective was to elucidate a functional method of differentiating between viable and non-viable organisms in environmental samples. The second objective was to use this and other more established microbiological analyses to characterize the microbial population inhabiting the block and determine if they influence elemental sulfur oxidation.In order to differentiate between viable and non-viable microorganisms, I relied on a DNA binding agent called ethidium monoazide bromide (EMA). Based on previous literature, I was able to test its activity in different environmental samples. Treatment with EMA inhibits the amplification of free DNA, whereas DNA protected by the membranes of viable cells is not affected. After finding that killed pure culture cells had a substantial reduction in their DNA amplification I proceeded to inoculate the same species of killed and viable cells into either soil, biofilm, or elemental sulfur samples obtained from Syncrude's Phase I sulfur block. I have found the EMA treatment to be sufficient at inhibiting amplification of DNA from non-viable cells inoculated into both the soil and sulfur samples, but not in the biofilms. In achieving the second objective I designed experiments which tested in vitro and in situ samples of the sulfur block. Bioreactors containing microbiological inoculants from water running off the sulfur block were compared to sterile bioreactors for levels of acidity, sulfate accumulation and microbial population. Comparison between the surface block samples and the matrix samples showed a higher number of bacteria in the surface samples; however, the differences between the two bioreactor treatments were not significant. Bioreactors which received sterile water did not increase in acidity or sulfate accumulation. The two treatments which were inoculated with 10% sulfur block run off increased by 3 and 4.3 mM sulfate, and 8.6 x 10-3 and 1.8 x 10-2 hydronium ion concentration, in the surface and matrix treatments respectively. In situ samples obtained by coring the sulfur blocks showed that microbial inhabitants are present throughout the block depth profile with a discontinuous pattern, which could be attributed to the fractures associated with the solidification of the block and subsequent colonization. The level of microbiological inhabitants ranged from 2.5 to 5.5 log heterotroph colony forming units g-1 sulfur, and 3.19 x 101 to 1.62 x 102 A. thiooxidans amplified copy numbers, and 1.23 x 103 to 1.11 x 104 Eubacteria amplified DNA copy numbers ìg-1 of extracted DNA from EMA treated sulfur block samples. Most probable number counts for autotrophs only detected organisms along the 0-10 cm depth of the block. The results of this study suggest that the use of ethidium monoazide bromide is a suitable method of detecting the large and varied microbial population inhabiting Alberta's sulfur blocks which can influence the level of block oxidation. The level of microorganisms present in the block is varied, which may parallel the varied pockets of air and water collected in the geomorphic fractures. Microbial communities residing in the sulfur block are partially responsible for sulfur oxidation. Methods aimed at reducing the level of sulfur oxidation must aim to reduce both the chemical and biological pathways leading to sulfur oxidation.
DegreeMaster of Science (M.Sc.)
SupervisorLawrence, John R.; Siciliano, Steven
CommitteeKorber, Darren R.; Germida, James J.; Deneer, Harry