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Date of Graduation
Master of Science (MS)
Department of Biology
Chytridiomycosis is an amphibian skin disease that threatens amphibian biodiversity worldwide. The infectious fungal agent of chytridiomycosis, Batrachochytrium dendrobatidis, can affect amphibians differently in that some amphibian populations can co-exist with the fungus and others quickly succumb to disease. Amphibians in populations that co-exist with the B. dendrobatidis are shown to have sub-lethal infections on their skins. Several co-existing populations have also been shown to have higher proportions of individuals with antifungal skin bacteria suggesting the role of skin bacteria in disease outcome. Little is known about the mechanism(s) that antifungal skin bacteria use to ameliorate the effects of B. dendrobatidis. In this study I identified that a B. dendrobatidis isolate JEL 310 zoospores (motile infectious phase) displays chemotaxis in the presence of two bacterially-produced metabolites (2,4-diacetylphloroglucinol and indole-3-carboxaldehyde). In the presence of either metabolite, B. dendrobatidis (JEL 310) zoospores are more likely to move away from the metabolites. Another B. dendrobatidis isolate JEL 423 did not display chemotaxis in the presence of violacein (bacterially-produced metabolite). Using parameters estimated from my B. dendrobatidis chemotaxis study, a mathematical model illustrates that B. dendrobatidis JEL 310 zoospores will disperse onto the source containing no metabolite if zoospores initially start both away from the source and on the source. The model illustrates that in the presence of a bacterially-produced 2,4-DAPG, B. dendrobatidis JEL 310 zoospores will disperse away from the source. These results suggest that amphibians that have skin bacteria that produce 2,4-DAPG might be able to keep B. dendrobatidis infections below the lethal threshold and thus be able to co-exist with the fungus.
Lam, Brianna Ashlyn, "Chemotaxis of amphibian pathogen batrachochytrium dendrobatidis in the presence and absence of antifungal metabolites produced by amphibian skin bacteria" (2010). Masters Theses, 2010-2019. 380.