Niche-specific features of the intestinal bacteroidales

Abstract

By analyzing the genomic sequences of 12 Bacteroidales species, we found that all intestinal species have numerous polysaccharide biosynthesis loci, many with promoters that we demonstrate undergo DNA inversion. This feature is not conserved in the Bacteroidales order as a whole, as oral species do not share these genetic features.

FIG. 1.

16S rRNA gene cladogram of members of the Bacteroidetes phylum for which there is a partial or complete genome sequence. Members of the Bacteroidales order are shown in color. The three families of Bacteroidales present in this cladogram are indicated. Within the Bacteroidales, oral species are in blue, the ruminal species is in green, and the intestinal species are in red.

FIG. 2.

DNA regions between each of the IRs undergo inversion. (A) Diagrammatic representation of the PCR method used to detect DNA inversions of each of the invertible promoter regions. Each of the primers contained within the IR (center primer) was used in a PCR with both the forward and reverse primers individually. (B) Ethidium bromide-stained agarose gels of PCR products, demonstrating inversion of the DNA between each of the IRs for each of the designated regions.