A changing understanding of the functional interactions between microbial communities and their associated hosts is influencing how disease is perceived and ameliorated. Of the numerous host-microbiome-disease systems of study, the emergence of chytridiomycosis in anurans (caused by Batrachochytrium dendrobatidis, hereafter Bd), has been implicated in ongoing declines and extinction events of amphibians across the planet. Interestingly, there has been differential survival among amphibians in resisting Bd infection and subsequent disease. One factor thought to contribute to this resistance is the host-associated cutaneous microbiota. This has raised the possibility of utilizing genetically modified probiotics to restructure the host-associated microbiota for desired anti-fungal outcomes. Here, we utilize a previously described strain of Serratia marcescens (Sm) for manipulation of amphibian cutaneous microbiota. Sm was genetically altered to have a dysfunctional pathway for the production of the extracellular metabolite prodigiosin. This genetically altered strain (Δpig) and the functional prodigiosin producing strain (WT-pig) were compared for their microbial community and anti-Bd effects both in vitro and in vivo. In vitro, Bd growth was significantly repressed in the presence of prodigiosin. In vivo, the inoculation of both Sm strains was shown to significantly influence amphibian microbiota diversity with the Δpig-Sm treatment showing increasing α-diversity, and the WT-pig S. marcescens having no temporal effect on diversity. Differences were also seen in host mortality with Δpig-Sm exhibiting significantly decreased survival probability as compared to a no¬-Sm control in the presence of Bd. These results are important evidence for the potential of genetic-level manipulation of bacteria in a host microbial community, which may provide a way to alter disease outcomes and address critical frontiers in disease and microbial ecology.