Date of Award

Spring 5-10-2025

Document Type

Honors Thesis

Department/Major

Biology

First Advisor

Jacob Kerby, Ph.D.

Second Advisor

David Swanson, Ph.D.

Third Advisor

Andrea Liebl, Ph.D.

Keywords

Prodigiosin, Batrachochytrium dendrobatidis, Serratia marcescens, Optical density

Subject Categories

Environmental Microbiology and Microbial Ecology

Abstract

Batrachochytrium dendrobatidis (Bd) is a pathogenic fungus that has been causing extirpations of amphibian species across the globe. The microbiome on the skin of amphibians is known to be a key factor in infection dynamics. It has been established that one species of cutaneous bacteria, Serratia marcescens, and a secondary metabolite with antifungal properties it produces, prodigiosin, has shown a promising ability to decrease the growth of Bd. However, when Serratia marcescens is grown in the same media with added metabolites produced by Bd, there is an observed decrease in the production of the bacteria’s protective metabolite, prodigiosin. This experiment examines the relationship between prodigiosin production and Bd metabolites at varying concentrations over two-degree temperature treatments (22°C to 32°C). Prodigiosin production was measured using UV spectrophotometry to calculate the optical density of the samples as a surrogate measure of metabolite concentration. Based on the results of this experiment, prodigiosin production is both temperature-and concentration-dependent, with the largest reduction occurring at lower temperatures with higher concentrations of Bd metabolites. For the first time, it has been discovered that Bd metabolites decrease prodigiosin production in Serratia marcescens. This finding has broader implications for microbial ecology, particularly in understanding amphibian cutaneous microbiomes and disease dynamics.

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