Theses and Dissertations at Montana State University (MSU)
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Item Aerobic bacterial methane synthesis in the human gastrointestinal tract(Montana State University - Bozeman, College of Agriculture, 2023) Jackson, Thomas Robert; Chairperson, Graduate Committee: Seth WalkAerobic bacterial methane synthesis constitutes a paradigm-shifting novel metabolism recently described in aquatic environments. It challenges the traditional model of methanogenesis as being a strictly anaerobic process carried out by archaeal methanogens. To date, the presence of aerobic bacterial methane synthesis has not been studied within the context of the human gastrointestinal tract. The goal of this work was to investigate the possibility of the presence of such metabolisms in the human gut microbiome. To investigate this, fecal samples from six individuals were first screened for the ability to produce methane under aerobic conditions. Bacteria from two of those fecal samples were isolated and evaluated for their ability to utilize methylamine, a known substrate involved in aerobic bacterial methane synthesis, as a sole nitrogen source. The ability of those isolates to produce methane under aerobic conditions from methylamine was then evaluated. Additionally, a flask-independent culture-based assay was developed in order to screen larger numbers of future isolates for the ability to utilize methylamine as a sole nitrogen source. This work demonstrates the first evidence of aerobic bacterial methane synthesis from members of the human gastrointestinal tract, finding two isolates capable of producing methane under aerobic conditions. Such findings broaden the understanding of methane-generating pathways that may have implications for the development of dysbiosis and atherosclerosis in human hosts.Item Studies on aerobic cellulose-decomposing bacteria(Montana State University - Bozeman, College of Agriculture, 1952) Nishio, JaneItem Studies on the cellulase produced by Aerobic Mesophilic bacteria(Montana State University - Bozeman, College of Agriculture, 1953) Hammerstrom, Richard A.Item Kinetics of calcite precipitation by ureolytic bacteria under aerobic and anaerobic conditions(Montana State University - Bozeman, College of Engineering, 2009) Parks, Stacy Leigh; Chairperson, Graduate Committee: Robin GerlachCarbonate precipitation is a natural phenomenon with a great importance in many chemical and engineering applications. Precipitation can be induced by bacteria as a by-product of common microbial processes, such as ureolysis. In this process, bacteria hydrolyze urea through a series of reactions which raise the pH of the system. In the presence of calcium ions, this rise in pH shifts the saturation state of the system, allowing for solid calcium carbonate (CaCO 3) to form. The use of these bacteria in biotechnical applications is appealing because urea is a fairly inexpensive substrate, and ureolytic bacteria are common in soil and aquatic environments. Bacteriogenic mineral plugging is an innovative use for this process. This technique controls subsurface fluid movement through the reduction of porosity and permeability of geologic formations, such as oil wells and aquifers. A potential use of this technology is in geologic carbon sequestration, which involves capturing CO 2 and storing it underground in deep saline aquifers. The goal of this project is to determine the kinetics of urea hydrolysis and CaCO 3 precipitation for use in the deep subsurface to mitigate potential leakage pathways of sequestered CO 2. To achieve this goal, three species of ureolytic bacteria, S. pasteurii, B. sphaericus strain 21776, and B. sphaericus strain 21787, were grown in batch systems under static conditions. Kinetic analysis was performed on the data gathered in these experiments. Due to the potential lack of oxygen in the deep subsurface, experiments using S. pasteurii were also carried out under anaerobic conditions. Because of the potential need to manipulate the rate of CaCO 3 precipitation to allow maximum distribution in the deep saline aquifers, the rates of urea hydrolysis and CaCO 3 precipitation among species and between aerobic and anaerobic conditions were compared. All three species studied were capable of inducing calcite precipitation. B. sphaericus strain 21776 exhibited the highest rate coefficient for both ureolysis and CaCO 3 precipitation, while B. sphaericus strain 21787 showed the lowest. S. pasteurii is capable of hydrolyzing urea and inducing calcite precipitation in anaerobic environments, although growth in these environments could not be shown conclusively.