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.


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Graduation Date





Santra, Swadeshmukul


Doctor of Philosophy (Ph.D.)


College of Sciences



Degree Program

Biomedical Sciences




CFE0008110; DP0023249





Release Date

February 2025

Length of Campus-only Access

5 years

Access Status

Doctoral Dissertation (Campus-only Access)

Restricted to the UCF community until February 2025; it will then be open access.