Masters Thesis

Identification and analysis of bacterial genes known to code for enzymes involved in the synthesis of cyclic lipopeptides and aminopolyol antibiotics

Infectious diseases are one of the world’s leading causes of death, and there is an increasing need for naturally occurring anti‐infectious agents to combat resistant strains of fungi and other pathogens. Numerous studies have demonstrated that metabolites, including antibiotics produced by antagonistic bacteria, play key roles in the control of various pathogens. In the southern San Joaquin valley, the non‐native North American Bullfrog (Lithobates catesbeianus) and the California Toad (Bufo boreas halophilus) seem to be thriving, whereas in general, amphibian species are in worldwide decline. The success of the bullfrog and the toad in the San Joaquin Valley may be credited to the antifungal compounds produced by their cutaneous bacterial microbiota. The purpose of this study is to determine if any of the cutaneous bacteria from the aforementioned bullfrog and toad possess genes involved in known antibiotic biosynthetic pathways. Specifically, this study utilizes PCR to determine if 17 previously identified antifungal isolates, possess specific antibiotic synthesis genes. The primer sets utilized in our study are associated with the genes that encode for the production of Fengycin, Iturin, Surfactin, Bacillomycin D and Zwittermicin A. It was determined that 1 isolate of the 17 harbors the gene, orf2, which is an integral component in the production of the antibiotic zwittermicin A. It was also determined that the same isolate, as well as three others harbor the zwittermicin A self‐resistance gene, zmaR. That all other isolates tested negative for the presence of any of the antibiotic biosynthesis genes tested, may implicate the presence of novel antibiotic compounds within cutaneous bacteria of the California Toad and North American bullfrog. With the emerging issue of antibiotic resistance facing our world today, discoveries like these may lead us towards finding new natural sources for antibiotic compounds.

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