(P20-027-23) Gut Microbiome Analysis of Captive Polar Bears

Objectives: Polar bears (Ursus maritimus), a hypercarnivorous Arctic species, prey almost exclusively on seals in winter and tend to fast much of the summer. Diet is one of the major predictors of gut and fecal microbiome composition in mammals. Additionally, relative abundance of gut microbes in the mammalian host can reflect host health, as microbes are fundamental to the metabolism and absorption of dietary nutrients. Our study seeks to compare the gut microbiome of captive polar bears. We hypothesize that no seasonal differences are detected given their steady diet of a commercial carnivore diet, fish, kibble, and vegetables.

Methods: We collected fecal samples from 24 individual polar bears from 10 zoos across the US (approved IACUC protocols on file from the Polar Bear Species Survival Plan Association and Towson University). Samples were shipped on ice, and frozen upon arrival. DNA was extracted using a Zymo DNA Miniprep kit and is currently being prepared for sequencing. Real-time qPCR is used to preliminarily determine the relative abundance of common bacterial taxa found in the gut of most mammals using taxon-specific primers relative to a primer recognizing Eubacteria. Furthermore, the metabolic activity of major taxonomic groups is being determined by quantitating short-chain fatty acids using GCMS.

Results: Our preliminary analyses demonstrate that bacterial phyla typical to terrestrial mammals, such as firmicutes, bacteroidetes, acidobacteria and actinobacteria, are detectable in the samples, with firmicutes being the most abundant phylum. Interestingly, a small seasonal shift in the relative abundance of bacterial taxa was noticeable for several individual polar bears. Furthermore, GCMS analyses confirmed that proprionate and butyrate are detectable in reasonable amounts in our samples.

Conclusions: As expected for a carnivorous species, firmicutes was the most abundant bacterial phylum detected in polar bears. Metagenomic sequencing analyses combined with GCSM data on bacterial metabolites will shed further light on the relative composition and complexity of the fecal microbiome of polar bears. This information may help target future dietary choices for captive polar bears, improving the wellbeing and mimicking natural conditions.

Funding Sources: Towson University Fischer College of Science & Mathematics