Theses and Dissertations at Montana State University (MSU)
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Item The optimal consortia of microbial bioremediation agents for the removal of heavy metals from the superfund site at newtown creek in brooklyn, new york(Montana State University, 2020) Korecki, Danielle Angela; Chairperson, Graduate Committee: Amaya Garcia-CostasBioremediation is a technique that introduces a microbial population capable of destroying, transforming, or immobilizing a pollutant of interest in a manner that is both safe to the environment and cost-effective. Bioremediation agents are effective in sequestering heavy metals, and are capable of functioning at their highest capacity when environmental conditions are complimentary to microbial growth, the indigenous microbial population favorably interacts with the introduced microorganisms, and nutritional requirements are satisfied either by the ecosystem or via the addition of amendments. Additionally, genetically engineered microorganisms can be utilized when necessary within especially challenging conditions. This study determines the ability of a consortia of microbial bioremediation agents to remove heavy metals from the Superfund site at Newtown Creek in Brooklyn, New York. The remediation of heavy metals at Newtown Creek can be accomplished using Rhodopseudomonas palustris, Saccharomyces cerevisiae, and Cupriavidus metallidurans. These microorganisms possess a high degree of potential and are promising tools in the reduction of Earth's ever-increasing pollution levels. Heavy metal concentrations, nutrient levels, pH, temperature, salinity, oxidation reduction potential, and the indigenous microbiome were analyzed to determine the expected benefit of microbial bioremediation in the reduction of heavy metal concentrations. Although high initial heavy metal concentrations and salinity may negatively impact this effort, all other variables are expected to be conducive to microbial growth. The introduction of amendments is expected to further benefit microbial bioremediation potential. The selected consortia of microorganisms introduced have the capacity to sequester all the chromium, lead, mercury, selenium, and silver found at Newtown Creek. The impact of arsenic, cadmium, copper, nickel, and zinc concentrations can also be decreased due to microbial bioremediation efforts. The use of genetically engineered microorganisms within a bioreactor is expected to further benefit remediation efforts for heavy metals sequestered at low rates within the natural environment. Microbial bioremediation is not expected to fully remove heavy metals from Newtown Creek, yet these microorganisms are capable of greatly improving conditions.Item Proteomics analysis of the metabolic transition between aerobic and anaerobic conditions in Escherichia coli(Montana State University - Bozeman, College of Letters & Science, 2019) Refai, Mohammed Yahya; Chairperson, Graduate Committee: Brian Bothner; Nina Paris, Hunter Fausset, Monika Tokmina Lukaszewska were co-authors of the article, 'Proteomics analysis of the transition between aerobic and anaerobic growth conditions in Escherichia coli' submitted to the journal 'Biochimica et biophysica acta' which is contained within this dissertation.As a facultative anaerobe, Escherichia coli has the ability to grow in anaerobic and aerobic environments. Despite detailed characterizations of this model organism in the presence and absence of oxygen, an in-depth understanding of changes to the proteome during transitions from aerobic to anaerobic growth is lacking. This thesis work focuses on elucidating how protein thiol oxidation and reduction change during a facultative anaerobe's transition from aerobic to anaerobic growth conditions, and pathways of thiol-mediated cell signaling. Redox driven changes in cysteine oxidation involved in signaling are referred to as 'thiol switches'. These modulate diverse biological activities ranging from gene expression and protein synthesis to environmental stress response. Surprisingly, little is known about the role of thiol switches during microbial transitions from aerobic and anaerobic growth conditions. To explore this uncharted territory, a mass-spectrometry (MS)-based proteomics workflow was developed and refined. Following extensive protocol optimization for high-throughput MS data processing, normalization, and pattern matching, the analytical pipeline was fine-tuned for the specific proteome-wide analysis of cysteine chemical modifications in E. coli. The approach was based on open-source software and publicly accessible databases, creating a transparent, reproducible, and easily sharable proteomics approach. Herein, the redox state and chemical forms of protein-based thiol switches in E. coli were characterized over time as the bacterium reversibly transitioned between aerobic and anaerobic growth conditions. Unexpectedly, differential alkylation analysis of cysteine-containing E. coli proteins revealed a higher degree of protein thiol oxidation under anaerobic growth conditions, a result not reported for E. coli or any other facultative anaerobe. Our proteome-wide analysis also revealed that cysteine redox potentials vary widely, and several specific E. coli proteins contain highly reactive thiols. These findings provide strong evidence for thiol-based signaling in E. coli in response to environmental changes such as aerobic to anaerobic growth transitions. Characterization of specific redox switches underlying metabolic changes associated with oxygen availability has uncovered a previously unknown E. coli cell signaling mechanism. Since transitioning between aerobic and anaerobic environments is associated with bacterial virulence, this work opens new avenues to target pathogenic facultative anaerobes and to develop novel thiol-based antibacterial therapies.Item Characterization of initial events of bacterial colonization at solid-water interfaces using image analysis(Montana State University - Bozeman, College of Engineering, 1990) Mueller, Robert FranzItem Colonization of a smooth surface by Pseudomanas aeruginosa : image analysis methods(Montana State University - Bozeman, College of Engineering, 1986) Escher, Andreas Rainer