Engineering Commons^™

Investigations Of Prokaryotic Defense Systems, Hannah Domgaard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bacteria are constantly threatened with infection by mobile genetic elements (MGE) such as bacteriophage and plasmids. Bacteriophage and plasmids require the bacteria's cellular infrastructure to replicate their genomes. Rampant replication can lead to cell death which is one reason why bacteria have developed a diverse array of immune systems to prevent or limit infection. This thesis studies three types of bacterial immune systems, type IV-A CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeat –CRISPR associated), type V-A2 CRISPR-Cas systems, and Wadjet systems.

The type IV-A system lies adjacent to a dinG-like helicase gene. Research has shown that this system can target …

Transesterification And Recovery Of Intracellular Lipids Using A Single Step Reactive Extraction, Daniel R. Nelson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A single-step, extractive reaction for extraction of lipids such as biodiesel components, omega-3 fatty acids, or other triglycerides from microbial cells was examined. Conventional methods for lipid extraction use toxic solvents, and require multiple steps and long processing times. When the goal is to produce fatty acid methyl esters or FAMEs, the extracted lipids are subjected to a separate transesterification reaction with simple alcohols in the presence of an acid or base catalyst. A simplified, single-step reactive extraction method can be applied that combines the sequential extraction followed by transesterification using acidified alcohols - a process known as in situ …

Nutrient Utilization From Anaerobic Digester Effluent Through Algae Cultivation, Shantanu Wahal

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nutrients present in digested animal waste can be utilized for algae cultivation under suitable conditions. Algal growth, however, depends on the chemical forms and speciation of these nutrients. In this study a chemical equilibrium model was first used to describe nutrient speciation and predict conditions that enhance the solubility of nutrients in anaerobic digester effluent. Dilution with water and separation of large particulates greatly improved nutrient availability and light penetration - conditions favorable for algal cultivation. Algae growth was tested using three strains - Scenedesmus dimorphous (UTEX # 417), Chlorella vulgaris (UTEX# 265), and an algal isolate (designated as LLAI …

Comparative Studies On Oxygen Mass Transfer For The Design And Development Of A Single-Use Fermentor, Kristan L. Sorenson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Accurate experimental oxygen mass transfer coefficient, a measure of how quickly oxygen travels from a gas bubble to the bulk liquid, is important for comparing performance and for evaluating the oxygen transfer capability of a fermentor. Delays in probe response and changing gas volumes upon start-up of gassing affect the accuracy of oxygen transfer measurements. To mitigate these inaccuracies, a standard correction procedure for oxygen mass transfer data was established for highly oxygenated, well-mixed fermentation systems. Probe response time correction was generated by applying a second-order response model to dissolved oxygen probes and shown to be effective within 4%. By …

Gene Expression Analysis Of Immobilized Saccharomyces Cerevisiae, Ryan Michael Summers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Immobilization is an effective method to increase ethanol production, as proven by previous research. Results almost exclusively demonstrate an increase in ethanol production by and decrease in reproduction rate of immobilized Saccharomyces cerevisiae cells. Recently, research has been conducted to determine the cause of this change. The extreme variance in results due to lack of technology makes it difficult to determine the cellular changes induced by immobilization. With the advent of new technology, specifically gene expression analysis, the RNA content of cells can be easily and rapidly analyzed.

S. cerevisiae cells were immobilized in 3% (w/v) calcium alginate beads and …

Development Of A Microelectrode Array Sensing System For Water Quality Monitoring, Robert D. Gardner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis reports the design and fabrication of a low-cost reliable microelectrode array sensing platform and its application toward water quality monitoring, including heavy metal ion detection. Individually addressable microelectrodes were designed in a planar array on a nonconductive glass substrate by a photolithography method. The size, shape, composition, and functionality of the microelectrodes were theoretically explored in order to maximize performance.

The microelectrode array sensing platform was proven and characterized in the K3Fe(CN)₆ electrochemical standard using cyclic voltammetry. The sensor platform exhibited well defined voltammograms and had increased sensitivity relative to a commercially available microelectrode of similar size. …