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The emerging infectious disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), infects the skin of amphibians and has been described as being responsible for the greatest loss of biodiversity of any known disease. It is directly associated with the extinction and decline of more than 200 species, has been found on every continent inhabited by amphibians, and is expanding in range. While there are currently no effective methods to prevent or treat infection in wild populations, supplementing the skin of amphibians with symbiotic antifungal bacteria has been suggested to mitigate the effects of disease. Janthinobacterium lividum, which produces the antifungal violet pigment violacein, has been isolated from the skin of various amphibians and inhibits the growth of Bd in laboratory assays. In the presence of the pathogen, higher survival is observed in both lab and field studies of amphibians that harbor this cutaneous microsymbiont. Disease management needs to be context-dependent and the identification of target populations with elevated disease susceptibility is required to make the most effective use of conservation funding and effort. Symbiotic bacteria of amphibian skin have been shown to be a subset of the microbial community of their habitat and J. lividum can be transmitted environmentally. This study aimed to develop a reliable and efficient method to test for the presence of J. lividum in small volumes (mL) of water sampled from amphibian habitats in the Hudson Valley, NY. Development of a polymerase chain reaction (PCR) method to detect Janthinobacterium sp. in water samples was not successful, but culture dependent techniques detected the presence of violet pigmented isolates most closely related to Janthinobacterium sp. and Iodobacter fluviatilis which are known violacein producers. Another violet pigmented isolate was found to be most closely related to Chitinomonas sp., which has not been previously reported to produce violacein. Future optimization of an analytically sensitive PCR program to detect Janthinobacterium sp. in water samples, characterization of the isolate related to Chitinomonas sp., and confirmation of the production of violacein in all violet pigmented isolates is warranted.
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Steckler, Veronica, "Environmental Detection of Bacteria with Antifungal Activity against the Amphibian Pathogen Batrachochytrium dendrobatidis: A Preliminary Survey of Janthinobacterium sp. in the Hudson Valley" (2012). Senior Projects Spring 2012. 95.