Theses and Dissertations

Issuing Body

Mississippi State University


Gordon, Donna M.

Committee Member

Thornton, Justin A.

Committee Member

Thibaudeau, Gissele

Committee Member

Lu, Shien

Date of Degree


Document Type

Dissertation - Open Access


Biological Sciences

Degree Name

Doctor of Philosophy (Ph.D)


College of Arts and Sciences


Department of Biological Sciences


Invasive fungal infections are a significant clinical challenge especially for hospitalized patients as traditional antifungal therapy often fails to resolve these infections. The ability of Candida to undergo yeast-to-hyphae morphological transition is central to this invasive behavior. Morphogenesis is also important for the formation of biofilms which are highly structured communities of microorganisms attached to one another or substratum and embedded within a protective extracellular matrix material. The refractory nature of cells within a biofilm to current antifungal therapies has created a need for alternative antifungal agents for the management of Candida biofilm-related infections. The novel antifungal occidiofungin is a natural product produced by the soil bacteria Burkholderia contaminans shown to be effective against a broad range of fungi including Candida spp. Prior studies have demonstrated that occidiofungin inhibits yeast-to-hyphae morphogenesis in the dimorphic yeast, C. albicans, likely through its impact on disrupting F-actin organization. To extend these findings, the efficacy of occidiofungin on morphogenesis of C. albicans and C. tropicalis strains under different inducing conditions was evaluated. Further, given the role of biofilm on pathogenicity, the anti-biofilm properties of occidiofungin against Candida species was examined using an in vitro static biofilm model developed on a silicon elastomer disk. The accumulated data indicate that occidiofungin inhibits hyphal transformation regardless of the inducing conditions used and prevents hyphal extension when added to cells post switching. Moreover, morphologically switching cells were more sensitive to occidiofungin than their yeast counterpart. In addition, occidiofungin effectively blocks biofilm formation at all stages of development and reduces dispersed cells from the biofilm for both C. albicans and C. tropicalis. Confocal data revealed alterations in actin organization with occidiofungin treatment for both morphologically switching and biofilm cells. These findings correlate with prior observations for occidiofungin activity on yeast form cells indicating the broad activity of occidiofungin against fungi at various stages of pathogenic growth and supports efforts to pursue occidiofungin as a potential therapeutic against Candida based infections.

Available for download on Friday, August 15, 2025

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