Environmental contamination by anthropogenic pollutants has steadily become a far- reaching problem. Despite the inherent toxicity, many microbial organisms are able to adapt and inhabit contaminated environments; some even metabolize the pollutants as a source of carbon and/or energy. The favorable metabolisms of these microbes may be utilized to effectively remove the pollutants through a process known as bioremediation. How one harnesses and manipulates the natural microbial community to achieve bioremediation of target pollutants is the focus of this thesis.
Biofilms are well known for their multifaceted tolerance to various pollutants. We hypothesized therefore that biofilms, cultivated directly from a contaminated environmental source, might be a choice strategy to harness microbes for use specifically in ex situ bioremediation of naphthenic acids (NAs) and polycyclic aromatic hydrocarbons (PAHs). This study examined the cultivation (and NA and PAH degradative capacity) of both mixed and single species biofilm and planktonic cultures from contaminated environments. Scalability and environmental performance were also examined.
All cultures derived from contaminated water and soil samples were capable of growing in the presence of synthetic mixtures of their respective contaminants, (NAs or PAHs) as determined by confocal microscopy and 16S rDNA qPCR. Of the 8 NAs tested, mixed communities degraded all but one, while single species cultures selectively degraded fewer NAs. Contrary to the hypothesis, biofilm and planktonic mixed communities exhibited comparable NA degradation. The initial microtiter device used to grow biofilms was successfully up scaled, and applied to existing wastewater treatment technology. Through life cycle assessment techniques, application of this technology for treating oil sands wastewater was deemed environmentally favorable over alternative, conventional practices. Overall, microbial communities were better able to degrade PAHs, although this varied for each soil inoculum source. Combined, the results of this thesis suggest that the ability to harness a diverse community of microbes from the environment as opposed to individual organisms is key for obtaining a population effective for ex situ biodegradation of NA and PAH hydrocarbons. Additionally, growth as a biofilm affords practical and logistical advantages making it more feasible to apply these communities in current ex situ bioremediation technologies.