Phylogenetic characterization of Centipeda periodontii, Selenomonas sputigena and Selenomonas species by 16S rRNA gene sequence analysis

The nearly complete 16S rRNA gene sequences for oral Gram-negative anaerobi c motile bacteria, Centipeda periodontii, Selenomonas sputigena and Selenom onas species (formerly S. sputigena type strain), were determined in order to unveil their relationship to other oral motile bacteria. To determine th e phylogenetic characterization of these bacteria, their 16S rRNA gene sequ ences were obtained and compared with those from the ribosomal sequence dat abases previously reported. The 16S rRNA gene sequences of these bacteria w ere similar to those of Selenomonas ruminantium and Schwartzia succinivoran s isolated from rumens, and to Pectinatus cerevisiiphilus isolated from spo iled beer. Among oral bacteria, the nucleotide sequence analysis of these b acteria revealed high nucleotide similarity to Veillonella species, whereas low similarity to oral motile bacteria such as Campylobacter species. Phyl ogenetic analysis clearly confirmed that C. periodontii and two Selenomonas species were classified as relatives of a group besides Selenomonas, Schwa rtzia, and Pectinatus species, and not as close relatives to oral motile ba cteria, such as Campylobacter species. These results suggest that such oral Gram-negative anaerobic motile bacteria are close relatives of oral bacter ia.