Optimization of the Production and Isolation of the Novel Antifungal Occidiofungin

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 DESCRIPTION (provided by applicant): Occidiofungin is a cyclic nonribosomally synthesized antifungal peptide with submicromolar fungicidal activity against a broad spectrum of fungi. Occidiofungin is produced by the Gram-negative bacterium Burkholderia contaminans. From our structural characterization studies, occidiofungin was determined to have a unique chemical composition. Our studies have also revealed that occidiofungin has a novel mechanism of action. Occidiofungin is a potent antifungal against fluconazole and caspofungin-resistant Candida albicans. Occidiofungin triggers cell death by inducing apoptosis in yeast cells. Occidiofungin has minimal toxicity in mice at doses exceeding 10 mg/kg. Furthermore, occidiofungin was shown to reduce Candida glabrata load in the kidneys of infected mice. All these studies point to the need to further the preclinical development of this novel compound. The major impediment to furthering investigational studies on this unique antifungal compound is the poor yield from culture liquor. The goal of this application is to enhance the yield and purity of occidiofungin following fermentation. Three approaches will be explored to increase the yield of the antifungal compound. First, media components will be screened to determine their effect on the production levels of the antifungal compound. Second, a molecular based approach will be used to determine whether an increase in production of occidiofungin is possible through genetic manipulation of B. contaminans. Our third approach is to develop a heterologous expression system. The last component of the application is to determine the most effective means of extracting and purifying the antifungal compound from the fermentation liquor. These studies will enable exploratory structure-activity relationship (SAR) studies on occidiofungin. This work is necessary for furthering additional studies aimed at developing the antifungal compound as a new therapeutic.