Matching Items (6)
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- All Subjects: Bacteria
- Creators: Abbaszadegan, Morteza
- Member of: Theses and Dissertations
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
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
The impact of physical/chemical properties of gray water on microbial inactivation in gray water using chlorine was investigated through creating artificial gray water in lab, varying specific components, and then measuring microbial inactivation. Gray water was made through taking autoclaved nanopure water, and increasing the concentration of surfacants, the turbidity, the concentration of organic content, and spiking E. coli grown in tryptic soy broth (TSB); chlorine was introduced using Clorox Disinfecting Bleach2. Bacteria was detected using tryptic soy agar (TSA), and E. coli was specifically detected using the selective media, brilliance. The log inactivation of bacteria detected using TSA was shown to be inversely related to the turbidity of the solution. Complete inactivation of E. coli concentrations between 104-105 CFU/100 ml in gray water with turbidities between 10-100 NTU, 0.1-0.5 mg/L of humic acid, and 0.1 ml of Dawn Ultra, was shown to occur, as detected by brilliance, at chlorine concentrations of 1-2 mg/L within 30 seconds. These result in concentration time (CT) values between 0.5-1 mg/L·min. Under the same gray water conditions, and an E. coli concentration of 104 CFU/100 ml and a chlorine concentration of 0.01 mg/L, complete inactivation was shown to occur in all trials within two minutes. These result in CT values ranging from 0.005 to 0.02. The turbidity and humic acid concentration were shown to be inversely related to the log inactivation and directly related to the CT value. This study shows that chlorination is a valid method of treatment of gray water for certain irrigation reuses.
ContributorsGreenberg, Samuel Gabe (Author) / Abbaszadegan, Morteza (Thesis director) / Schoepf, Jared (Committee member) / Alum, Absar (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Is it possible to treat the mouth as a natural environment, and determine new methods to keep the microbiome in check? The need for biodiversity in health may suggest that every species carries out a specific function that is required to maintain equilibrium and homeostasis within the oral cavity. Furthermore, the relationship between the microbiome and its host is mutually beneficial because the host is providing microbes with an environment in which they can flourish and, in turn, keep their host healthy. Reviewing examples of larger scale environmental shifts could provide a window by which scientists can make hypotheses. Certain medications and healthcare treatments have been proven to cause xerostomia. This disorder is characterized by a dry mouth, and known to be associated with a change in the composition, and reduction, of saliva. Two case studies performed by Bardow et al, and Leal et al, tested and studied the relationships of certain medications and confirmed their side effects on the salivary glands [2,3]. Their results confirmed a relationship between specific medicines, and the correlating complaints of xerostomia. In addition, Vissink et al conducted case studies that helped to further identify how radiotherapy causes hyposalivation of the salivary glands [4]. Specifically patients that have been diagnosed with oral cancer, and are treated by radiotherapy, have been diagnosed with xerostomia. As stated prior, studies have shown that patients having an ecologically balanced and diverse microbiome tend to have healthier mouths. The oral cavity is like any biome, consisting of commensalism within itself and mutualism with its host. Due to the decreased salivary output, caused by xerostomia, increased parasitic bacteria build up within the oral cavity thus causing dental disease. Every human body contains a personalized microbiome that is essential to maintaining health but capable of eliciting disease. The Human Oral Microbiomics Database (HOMD) is a set of reference 16S rRNA gene sequences. These are then used to define individual human oral taxa. By conducting metagenomic experiments at the molecular and cellular level, scientists can identify and label micro species that inhabit the mouth during parasitic outbreaks or a shifting of the microbiome. Because the HOMD is incomplete, so is our ability to cure, or prevent, oral disease. The purpose of the thesis is to research what is known about xerostomia and its effects on the complex microbiome of the oral cavity. It is important that researchers determine whether this particular perspective is worth considering. In addition, the goal is to create novel experiments for treatment and prevention of dental diseases.
ContributorsHalcomb, Michael Jordan (Author) / Chen, Qiang (Thesis director) / Steele, Kelly (Committee member) / Barrett, The Honors College (Contributor) / College of Letters and Sciences (Contributor)
Created2015-05
Description
This thesis research focuses on phylogenetic and functional studies of microbial communities in deep-sea water, an untapped reservoir of high metabolic and genetic diversity of microorganisms. The presence of photosynthetic cyanobacteria and diatoms is an interesting and unexpected discovery during a 16S ribosomal rRNA-based community structure analyses for microbial communities in the deep-sea water of the Pacific Ocean. Both RT-PCR and qRT-PCR approaches were employed to detect expression of the genes involved in photosynthesis of photoautotrophic organisms. Positive results were obtained and further proved the functional activity of these detected photosynthetic microbes in the deep-sea. Metagenomic and metatranscriptomic data was obtained, integrated, and analyzed from deep-sea microbial communities, including both prokaryotes and eukaryotes, from four different deep-sea sites ranging from the mesopelagic to the pelagic ocean. The RNA/DNA ratio was employed as an index to show the strength of metabolic activity of deep-sea microbes. These taxonomic and functional analyses of deep-sea microbial communities revealed a `defensive' life style of microbial communities living in the deep-sea water. Pseudoalteromonas sp.WG07 was subjected to transcriptomic analysis by application of RNA-Seq technology through the transcriptomic annotation using the genomes of closely related surface-water strain Pseudoalteromonas haloplanktis TAC125 and sediment strain Pseudoalteromonas sp. SM9913. The transcriptome survey and related functional analysis of WG07 revealed unique features different from TAC125 and SM9913 and provided clues as to how it adapted to its environmental niche. Also, a comparative transcriptomic analysis of WG07 revealed transcriptome changes between its exponential and stationary growing phases.
ContributorsWu, Jieying (Author) / Meldrum, Deirdre R. (Thesis advisor) / Zhang, Weiwen (Committee member) / Abbaszadegan, Morteza (Committee member) / Neuer, Susanne (Committee member) / Arizona State University (Publisher)
Created2013
Description
Legionella is a gram-negative bacterium with the ability for human infection by inhalation or aspiration of water containing the bacteria. Legionella live in aquatic environments and have been identified in cooling towers, humidifiers and respiratory therapy treatments, among others. Infection with Legionella bacteria leads to Legionnaire’s Disease or Pontiac Fever (Edelstein, 1993). Information regarding the means of aerosolization of Legionella bacteria has not yet been reported, therefore the relevance of experimentation was defined. The objective of this study is to determine the modes by which bacteria may be aerosolized under laboratory conditions. Specifically, to measure the amount of bacteria transported over a specific distance in a given amount of time and determine the most effective mode of bacterial aerosolization. Three methods of bacterial aerosolization were tested, these included an electric paint sprayer, an air paint sprayer and a hand-held spray bottle. E. coli was used as a surrogate for Legionella in experimentation due to its similar bacterial properties. Both bacteria are gram-negative, aerobic bacilli while Legionella is approximately 2 μm in length (Botzenhart, 1998), and E. coli is between 1 and 3 μm in length (Reshes, 2007). The accessibility and non-pathogenicity of E. coli also served as factors for the substitution.
In order to measure the aerosolization efficiency of each spray method, an air sampler was placed opposite to the position of the sprayer, on either side of a sealed box. Each sprayer was filled with E. coli concentrated at 104 CFU/ml in a PBS solution and sprayed for a time span of 1 and 5 seconds. For each of these time intervals an air sample was collected immediately following the spray as well as 5 minutes after the spray. Compared to the other two methods, the air spray method consistently showed the highest number of bacterial cells aerosolized. While all three methods resulted in the aerosolization of bacteria, the results determined the Air Spray method as the most efficient means of bacterial aerosolization. In this study, we provide a practical and efficient method of bacterial aerosolization for microbial dispersion in air. The suggested method can be used in future research for microbial dispersion and transmission studies.
In addition, a humidifier was filled with a spiked solution of E. coli and operated for a period of 1 and 5 seconds at its maximum output. Air samples were collected after 0 and 5 minutes. Immediately after the humidifier operation was stopped a small number of colonies were detected in the air sample and no colonies were detected in the air sample collected after a 5-minute elapsed time. This experiment served as a proof of concept for airborne pathogen’s transmission by a humidifier.
In order to measure the aerosolization efficiency of each spray method, an air sampler was placed opposite to the position of the sprayer, on either side of a sealed box. Each sprayer was filled with E. coli concentrated at 104 CFU/ml in a PBS solution and sprayed for a time span of 1 and 5 seconds. For each of these time intervals an air sample was collected immediately following the spray as well as 5 minutes after the spray. Compared to the other two methods, the air spray method consistently showed the highest number of bacterial cells aerosolized. While all three methods resulted in the aerosolization of bacteria, the results determined the Air Spray method as the most efficient means of bacterial aerosolization. In this study, we provide a practical and efficient method of bacterial aerosolization for microbial dispersion in air. The suggested method can be used in future research for microbial dispersion and transmission studies.
In addition, a humidifier was filled with a spiked solution of E. coli and operated for a period of 1 and 5 seconds at its maximum output. Air samples were collected after 0 and 5 minutes. Immediately after the humidifier operation was stopped a small number of colonies were detected in the air sample and no colonies were detected in the air sample collected after a 5-minute elapsed time. This experiment served as a proof of concept for airborne pathogen’s transmission by a humidifier.
ContributorsJohnson, Chelsea Elizabeth (Author) / Abbaszadegan, Morteza (Thesis director) / Stout, Valerie (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
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