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Canine fecal metagenome

The current study is the first to utilize a metagenomics approach to characterize the phylogeny and functional capacity of the canine gastrointestinal microbiome. Six healthy adult dogs were used in a crossover design and fed a low-fiber control diet (K9C) or one containing 7.5% beet pulp (K9BP). Pooled fecal DNA samples from each treatment were subjected to 454 pyrosequencing, generating 422,653 (K9C) and 505,061 (K9BP) sequences. Dominant bacterial phyla included the Bacteroidetes/Chlorobi group and Firmicutes, both of which comprised approx. 35% of all sequences, followed by Proteobacteria (13-15%), and Fusobacteria (7-8%). K9C had a greater percentage of Bacteroidetes, Fusobacteria, and Proteobacteria, while K9BP had greater proportions of the Bacteroidetes/Chlorobi group and Firmicutes. Archaea were not altered by diet and represented approx. 1% of all sequences. All archaea were members of Crenarchaeota and Euryarchaeota, with methanogens being the most abundant and diverse. Three fungal phylotypes were present in K9C, but none in K9BP. Less than 0.4% of sequences were of viral origin, with >99% of those associated with bacteriophages. Primary functional categories were not greatly affected by diet and were associated with carbohydrates; protein metabolism; DNA metabolism; cofactors, vitamins, prosthetic groups, and pigments; amino acids and derivatives; cell wall and capsule; and virulence. Hierarchical clustering of several gastrointestinal metagenomes demonstrated high phylogenetic and metabolic similarity between dogs, humans, and mice. More research is needed to provide deeper coverage of the canine microbiome, evaluate effects of age, genetics, or environment on its composition and activity, and identify its role in gastrointestinal disease.