Antimicrobial resistance development is a global concern. A handful of effective treatments are currently available for controlling bacterial disease in animal and plant systems. In humans, overuse of antibiotics poses a serious threat. In the United States, over two million nosocomial infections are reported annually for which traditional antibiotic treatments are often ineffective, requiring a high-risk aggressive treatment of cocktail antibiotics. Copper (Cu)-based biocides are currently the standard for controlling bacterial and fungal diseases of many crops. However, there is an increasing concern of resistance development and non-target environmental toxicity of Cu biocides to aquatic species and other beneficial organisms. To reduce Cu input in the environment and combat against Cu resistance, high-performing Cu or Cu alternatives must be developed. In this dissertation research, a few novel alternatives to traditional antimicrobial compounds (antibiotics and Cu) were developed and studied. A composite of Gallium and N-Acetyl Cysteine (Ga-NAC) as an alternative to conventional antibiotics was studied for treating Pseudomonas aeruginosa infections. The Ga-NAC composite treatment revealed strong anti-biofilm properties, exhibiting a high therapeutic window. Improved Ga bioavailability at the cell surface is linked to enhanced intracellular uptake and killing. Two novel composite materials were developed against Xanthomonas citri subsp. citri, a pathogen responsible for citrus canker disease. A composite of zinc oxide and nano-copper (ZnO-n-Cu) was developed to reduce Cu application rate. Performance of the ZnO-n-Cu composite in field conditions was evaluated in a commercial grove for two consecutive years. The ZnO-n-Cu composite suppressed citrus canker disease at five times lower copper concentration in comparison to Cu standards. Another composite material of silica gel and quaternary ammonium compound (Fixed-Quat) was developed and tested as a non-metal alternative to copper biocide. Fixed-Quat demonstrated similar field efficacy against citrus canker when compared to Cu standards for three consecutive seasons.
If this is your thesis or dissertation, and want to learn how to access it or for more information about readership statistics, contact us at STARS@ucf.edu
Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Campus-only Access)
Young, Mikaeel, "Strategies for Improving Efficacy of Metal and Non-metal Based Antimicrobial Agents" (2019). Electronic Theses and Dissertations. 6857.
Restricted to the UCF community until February 2025; it will then be open access.