Distribution Analysis of Six Predominant Bacteroides Species in Normal Human Feces Using 16S rDNA-Targeted Species-Specific Primers

In order to analyze the predominant Bacteroides species in normal human feces, species-specific primer sets for Bacteroides eggerthii , B. fragilis , B. ovatus , B. thetaiotaomicron , B. uniformis and B. vulgatus were designed. Normal human feces were cultured on Bacteroides selective agar (neomycin brilliant green taurocolic acid (NBGT) agar plates). We identified the colonies with the aforementioned species-specific primers. B. vulgatus and B. ovatus were found to be predominant in all volunteers, and B. thetaiotaomicron and B. uniformis varied between volunteers. However, B. fragilis and B. eggerthii were not detected in any volunteers using this culture method. When we used the direct PCR method with extracted bacterial DNA from feces, B. vulgatus and B. ovatus were detected from all samples, and B. thetaiotaomicron , B. uniformis and B. fragilis from four or five out of six samples, but no B. eggerthii was detected. This is the first report that analyzes the predominant Bacteroides species in normal human intestine using a systematic molecular identification method. Keywords: Bacteroides , 16S rRNA, species-specific primer, human, feces.