Faculty Mentor

Dr. Jenifer Walke

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Chytridiomycosis, an amphibian skin disease caused by a chytrid fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been linked to global amphibian declines. Some amphibian populations are resistant to severe infection due to symbiotic antifungal skin bacteria, but attempts to develop probiotics from these bacteria have been inconsistently successful because bacteria fail to persist on the skin. Studies have largely been conducted on adult and juvenile amphibians, despite amphibians having fewer known mechanisms for microbiome regulation prior to metamorphosis. We hypothesize that probiotics will persist longer and thus be more effective against pathogen infection if they are applied at an early life stage. We conducted a laboratory study to test the effectiveness of bacterial probiotic applications to Rana luteiventris eggs, tadpoles immediately after hatching, tadpoles one week after hatching, and newly metamorphosed frogs. Temperature is known to play a role in Bd infection dynamics as well as microbiome composition, so two temperature regimes based on current and modeled future temperatures were used in the experiment. We exposed all treatment groups to Bd following metamorphosis and swabbed to collect skin microbiome samples. To evaluate the host-microbiome-pathogen dynamics, we will analyze 16S rRNA gene amplicon sequencing and Bd qPCR data. This research will inform future probiotic strategies to combat a pathogen contributing to significant amphibian declines.