Matching Items (3)
Filtering by
- All Subjects: Bacteria
- Creators: Fox, Peter
Description
Nanotechnology is a scientific field that has recently expanded due to its applications in pharmaceutical and personal care products, industry and agriculture. As result of this unprecedented growth, nanoparticles (NPs) have become a significant environmental contaminant, with potential to impact various forms of life in environment. Metal nanoparticles (mNPs) exhibit unique properties such as increased chemical reactivity due to high specific surface area to volume ratios. Bacteria play a major role in many natural and engineered biogeochemical reactions in wastewater treatment plants and other environmental compartments. I have evaluated the laboratory isolates of E. coli, Bacillus, Alcaligenes, Pseudomonas; wastewater isolates of E. coli and Bacillus; and pathogenic isolate of E. coli for their response to 50 & 100 nm sized Cu nanoparticles (CuNPs). Bactericidal tests, scanning electron microscopy (SEM) analyses, and probable toxicity pathways assays were performed. The results indicate that under continuous mixing conditions, CuNPs are effective in inactivation of the selected bacterial isolates. In general, exposure to CuNPs resulted in 4 to >6 log reduction in bacterial population within 2 hours. Based on the GR, LDH and MTT assays, bacterial cells showed different toxicity elicitation pathways after exposure to CuNPs. Therefore, it can be concluded that the laboratory isolates are good candidates for predicting the behavior of environmental isolates exposed to CuNPs. Also, high inactivation values recorded in this study suggest that the presence of CuNPs in different environmental compartments may have an impact on pollutants attenuation and wastewater biological treatment processes. These results point towards the need for an in depth investigation of the impact of NPs on the biological processes; and long-term effect of high load of NPs on the stability of aquatic and terrestrial ecologies.
ContributorsAlboloushi, Ali (Author) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Fox, Peter (Committee member) / Olson, Larry (Committee member) / Arizona State University (Publisher)
Created2012
Description
Agrobacterium tumefaciens has the ability to transfer its tumor inducing (Ti) plasmid into plant cells. In the last decade, agroinfiltration of Nicotiana benthamiana plants has shown promising results for recombinant protein production. However, A. tumefaciens produce endotoxins in the form of lipopolysaccharides (LPS), a component of their outer membrane that can induce organ failure and septic shock. Therefore, we aimed to detoxify A. tumefaciens by modifying their Lipid A structure, the toxic region of LPS, via mutating the genes for lipid A biosynthesis. Two mutant strains of A. tumefaciens were infiltrated into N. benthamiana stems to test for tumor formation to ensure that the detoxifying process did not compromise the ability of gene transfer. Our results demonstrated that A. tumefaciens with both single and double mutations retained the ability to form tumors. Thus, these mutants can be utilized to generate engineered A. tumefaciens strains for the production of plant-based pharmaceuticals with low endotoxicity.
ContributorsHaseefa, Fathima (Author) / Chen, Qiang (Thesis director) / Mason, Hugh (Committee member) / Hurtado, Jonathan (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Nitrogen removal and energy reduction in wastewater treatment are shared goals. Approaches to achieve those goals include the techniques of shortcut nitrogen removal utilizing nitrite shunt, biocatalyst, nitritation, deammonification, and simultaneous nitrification-denitrification. The practice of those techniques is newer in the industry of wastewater treatment but continues to develop, along with the understanding of the biological and chemical activities that drive those processes. The kinetics and stoichiometry of traditional and shortcut nitrogen removal reactions are generally well understood to date. However, the thermodynamics of those processes are complex and deserve additional research to better understand the dominant factors that drive cell synthesis. Additionally, the implementation of nitrogen shortcut techniques can reduce the footprint of wastewater treatment processes that implement nitrogen removal by approximately 5 percent and can reduce operating costs by between 12 and 26 percent annually. Combined, nitrogen shortcut techniques can contribute to significant reduction in the long-term cost to operate, due to lower energy and consumable requirements, fast reaction times resulting in shorter solids retention times, and improvement efficiency in nitrogen removal from wastewater. This dissertation explores and defines the dominant factors that contribute to the success of efficiencies in traditional and shortcut nitrogen removal techniques, focusing on the natural microbiological processes. The culmination of these efforts was used to develop decision matrices to promote consideration of nitrogen shortcut techniques by practitioners during conceptual planning and design of wastewater treatment facilities.
ContributorsTack, Frederick Henry (Author) / Fox, Peter (Thesis advisor) / Krajmalnik-Brown, Rosa (Committee member) / Abbaszadegan, Morteza (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2021