Microbial flocculation is important in wastewater treatment process for an efficient separation of the solid and liquid phases and the removal of organics. Bacterial adhesins may contribute to the formation of microbial flocs since they have been previously found to play a significant role in the formation of biofilms. The overall objective of this work was to analyze bacterial protein adhesins present in the extracellular polymeric substances (EPS), mainly those associated with pili, fimbriae, flagella, and curli, and to determine their role in microbial floc structure and function. Identification of these EPS adhesins may explain their role in biofouling and enhance our understanding regarding the manipulation of bioflocculation. With the exception of flagellin protein FliC, which was distributed towards the outer region of the floc, all the adhesins appeared to be concentrated within the core region of the floc. Antibody staining coupled with confocal microscopy indicated that adhesin proteins associated with flagella (FliC), pili (PilA), fimbriae (FimH), and curli (CsgA, CsgB) represent a significant fraction (10-27%) within microbial flocs. Western blot analyses demonstrated that with the exception of FliC, all the studied adhesins were detected in the EPS matrix. Furthermore, mass spectrometry indicated the presence of pili in the EPS matrix. Under Phosphorus (P)-limited conditions, with the exception of fliC, all the studied genes (fimH, pilO, psiF) exhibited a change in response to P reduction, with fimH gene at the highest expression and an earliest response (1 d). During the nutritional downshift analyses, fimH and pilO genes were expressed within the first six hours of the reaction at significantly greater levels than during P-limited conditions. Taken together, these studies suggest that adhesins associated with pili, fimbriae, and curli play an important role in initial floc formation, and that adhesins associated with flagella either recruit planktonic bacteria to a growing floc or are involved in the interfacial relationships at the floc surface. This information may assist researchers and engineers in broadening the understanding of bioflocculation in conventional biologically based wastewater treatment systems and in advanced technologies, such as hybrid and membrane bioreactors. In addition, this knowledge will be useful in creating molecular tools to aid in the design and monitoring of bioflocculation.

In this thesis, I have produced low polydispersity polymers of poly(chloromethylstyrene) and polyvinylphenol. Modification reactions for both polymers were attempted and were successful for only poly(chloromethylstyrene) as conditions in our experiments produced insoluble polymer salts using polyvinylphenol. A set of modified polymers were produced using a low polydisperse poly(chloromethylstyrene) as we believe that polymers with PDIs < 1.4 will be preferable for use in an eventual solar cell device. Finally a set of experiments were completed to determine the conditions to minimize the PDI of poly(chloromethylstyrene) and found that the main variable was maximizing the amount of 3-chloromethylstyrene with respect to 4-chloromethylstyrene in a polymerization. This result has lead us to believe that 3-chloromethylstyrene is less prone to transfer reactions, which in turn leads to smaller PDI values.

Nanoporosity formation by selective dissolution of Ag-5 at. pct Au in perchloric acid has been investigated with regards to the mechanism of stress-corrosion cracking (SCC), film-induced cleavage in particular. It has been proven that dealloying of silver-gold systems containing low concentration of gold leads to the formation of a three dimensional nanoporous layer and that it can be carried out in a broad range of potentials and concentrations of a dealloying solution. Therefore, stress-corrosion cracking observed in these alloys may be caused, initiated or at least accompanied by the formation of nanoporosity resulting from dealloying. These results will have impact on the fabrication of cheaper nanomaterials where there is required large surface to volume ratio with gold as the outermost layer. Understanding the role of dealloying will also help us to design new materials of higher resistance against stress-corrosion cracking.

Models of aqueous metal speciation and ecotoxicity have become commonplace due to their ability to estimate metal behaviour. This study evaluated commonly used aqueous geochemical speciation and ecotoxicity models with application to a mine impacted lake in northern Manitoba. The geochemical speciation model Winderemere Humic Aqueous Model (WHAM) was compared with Diffusive Gradients in Thinfilm (DGT) measurements of zinc and copper. DGT measurements in the water column corresponded well with WHAM-estimated Zn2+, Cu2+ was off by up to 100x. Additional metal, either from small organic bound species or dissolution of metal sulphides from resuspended sediment, served to improve model estimates. The single metal Biotic Ligand Model (BLM) predicted acute toxicity to Daphnia magna attributable to copper but not zinc, at low pH (3.55 – 5.5). Comparison of results did not show a significant difference between the single and mixture BLMs, suggesting a non-interactive effect on metal toxicity for measured water chemistry.

Odour emissions resulting from reduced sulphur compounds in the kraft pulping industry are frequently found in dilute, high flowrate air streams that are costly to treat using incineration and thermal oxidation. Biofiltration, an air treatment method involving passing air through a packed bed of microorganisms, has emerged as a promising treatment strategy for these dilute waste gas streams. However, biodegradation of dimethyl sulphide (DMS) in biofilters is rather poor and is limiting the application of biofiltration to odour streams rich in DMS. Recently, our group has shown that co-treatment of DMS with methanol can increase DMS removal significantly. In this thesis, the effect of methanol on the microbiology of two biofilters treating DMS was explored. Microbial community analysis revealed that the addition of methanol led to a significant increase of up to an order of magnitude in the abundance of Hyphomicrobium spp. in a biofilter co-treating DMS and methanol compared to a biofilter treating DMS alone with no significant difference in the abundance of Thiobacillus spp. between the two biofilters. Further to the biofiltration experiments, the growth kinetics of Hyphomicrobium spp. and Thiobacillus spp. on DMS and methanol in an enrichment culture created from a biofilter co-treating DMS and methanol were studied. A specific growth rate of 0.099 h-1 and 0.11 h-1 was determined for Hyphomicrobium spp. and Thiobacillus spp., respectively, growing on DMS at pH 7, double the highest maximum specific growth rate for bacterial growth on DMS reported to date in the literature. As the pH decreased from pH 7 to pH 5, the specific growth rate of Hyphomicrobium spp. decreased significantly by 85% in the mixed culture while the specific growth rate of Thiobacillus spp. remained similar through the same pH shift. When methanol was used as a substrate, the specific growth rate of Hyphomicrobium spp. declined much less over the same pH range (up to 30%). These results suggest that addition of methanol to biofilters co-treating DMS and methanol can increase DMS removal rates by increasing the abundance of DMS-degrading Hyphomicrobium spp. at pH levels not conducive to high growth rates on DMS alone.

Microbial flocculation is important in wastewater treatment process for an efficient separation of the solid and liquid phases and the removal of organics. Bacterial adhesins may contribute to the formation of microbial flocs since they have been previously found to play a significant role in the formation of biofilms. The overall objective of this work was to analyze bacterial protein adhesins present in the extracellular polymeric substances (EPS), mainly those associated with pili, fimbriae, flagella, and curli, and to determine their role in microbial floc structure and function. Identification of these EPS adhesins may explain their role in biofouling and enhance our understanding regarding the manipulation of bioflocculation. With the exception of flagellin protein FliC, which was distributed towards the outer region of the floc, all the adhesins appeared to be concentrated within the core region of the floc. Antibody staining coupled with confocal microscopy indicated that adhesin proteins associated with flagella (FliC), pili (PilA), fimbriae (FimH), and curli (CsgA, CsgB) represent a significant fraction (10-27%) within microbial flocs. Western blot analyses demonstrated that with the exception of FliC, all the studied adhesins were detected in the EPS matrix. Furthermore, mass spectrometry indicated the presence of pili in the EPS matrix. Under Phosphorus (P)-limited conditions, with the exception of fliC, all the studied genes (fimH, pilO, psiF) exhibited a change in response to P reduction, with fimH gene at the highest expression and an earliest response (1 d). During the nutritional downshift analyses, fimH and pilO genes were expressed within the first six hours of the reaction at significantly greater levels than during P-limited conditions. Taken together, these studies suggest that adhesins associated with pili, fimbriae, and curli play an important role in initial floc formation, and that adhesins associated with flagella either recruit planktonic bacteria to a growing floc or are involved in the interfacial relationships at the floc surface. This information may assist researchers and engineers in broadening the understanding of bioflocculation in conventional biologically based wastewater treatment systems and in advanced technologies, such as hybrid and membrane bioreactors. In addition, this knowledge will be useful in creating molecular tools to aid in the design and monitoring of bioflocculation.

Over the past decade, the constraint-based approach to metabolic modeling has become an important tool for understanding and controlling biology. Unfortunately, the application of this novel approach to systems biology in biotechnology has been limited by three significant technical issues: existing metabolic modeling methods cannot completely model the overflow metabolism, cannot model the metabolism of microbial communities, and cannot design strains optimized for productivity and titer. Three computational methods – the Flux Balance Analysis with Membrane Economics (FBAME) method, the Dynamic Multi-species Metabolic Modeling (DyMMM) framework, and the Dynamic Strain Scanning Optimization (DySScO) strategy – have been developed to resolve these issues respectively. First, the FBAME method, which adopts the membrane occupancy limitation hypothesis, was used to explain and predict the phenomenon of overflow metabolism, an important metabolic phenomenon in industrial fermentation, in Escherichia coli. Then, the DyMMM framework was used to investigate the community metabolism during uranium bioremediation, and demonstrated that the simultaneous addition of acetate and Fe(III) may be a theoretically viable uranium bioremediation strategy. Lastly, the DySScO strategy, which combines the DyMMM framework with existing strain design algorithms, was used to design commodity-chemical producing E. coli optimized for a balanced product yield, titer, and volumetric productivity. These novel computational methods allow for broader applications of constraint-based metabolic models in biotechnology settings.

In this thesis, I have produced low polydispersity polymers of poly(chloromethylstyrene) and polyvinylphenol. Modification reactions for both polymers were attempted and were successful for only poly(chloromethylstyrene) as conditions in our experiments produced insoluble polymer salts using polyvinylphenol. A set of modified polymers were produced using a low polydisperse poly(chloromethylstyrene) as we believe that polymers with PDIs < 1.4 will be preferable for use in an eventual solar cell device. Finally a set of experiments were completed to determine the conditions to minimize the PDI of poly(chloromethylstyrene) and found that the main variable was maximizing the amount of 3-chloromethylstyrene with respect to 4-chloromethylstyrene in a polymerization. This result has lead us to believe that 3-chloromethylstyrene is less prone to transfer reactions, which in turn leads to smaller PDI values.

Nanoporosity formation by selective dissolution of Ag-5 at. pct Au in perchloric acid has been investigated with regards to the mechanism of stress-corrosion cracking (SCC), film-induced cleavage in particular. It has been proven that dealloying of silver-gold systems containing low concentration of gold leads to the formation of a three dimensional nanoporous layer and that it can be carried out in a broad range of potentials and concentrations of a dealloying solution. Therefore, stress-corrosion cracking observed in these alloys may be caused, initiated or at least accompanied by the formation of nanoporosity resulting from dealloying. These results will have impact on the fabrication of cheaper nanomaterials where there is required large surface to volume ratio with gold as the outermost layer. Understanding the role of dealloying will also help us to design new materials of higher resistance against stress-corrosion cracking.

Models of aqueous metal speciation and ecotoxicity have become commonplace due to their ability to estimate metal behaviour. This study evaluated commonly used aqueous geochemical speciation and ecotoxicity models with application to a mine impacted lake in northern Manitoba. The geochemical speciation model Winderemere Humic Aqueous Model (WHAM) was compared with Diffusive Gradients in Thinfilm (DGT) measurements of zinc and copper. DGT measurements in the water column corresponded well with WHAM-estimated Zn2+, Cu2+ was off by up to 100x. Additional metal, either from small organic bound species or dissolution of metal sulphides from resuspended sediment, served to improve model estimates. The single metal Biotic Ligand Model (BLM) predicted acute toxicity to Daphnia magna attributable to copper but not zinc, at low pH (3.55 – 5.5). Comparison of results did not show a significant difference between the single and mixture BLMs, suggesting a non-interactive effect on metal toxicity for measured water chemistry.