Usefulness of the hsp60 gene for the identification and classification of Gram-negative anaerobic rods.

The hsp60 gene sequences were determined for 121 strains of Gram-negative anaerobic rods, including the genera Bacteroides, Barnesiella, Butyricimonas, Odoribacter, Parabacteroides, Paraprevotella, Porphyromonas, Prevotella and Tannerella. The mean pairwise hsp60 gene sequence similarity (73.8-97.1 %) between species in each genus, except for the genus Tannerella that comprises one species, was significantly less than that of the 16S rRNA gene sequence (88.3-96.3 %). Only pairwise hsp60 gene sequence similarity (97.1 %) of the genus Paraprevotella was higher than that of the 16S rRNA gene sequence (93.8 %). Each genus formed a distinct clade in the phylogenetic analysis of the hsp60 gene sequence as well as the 16S rRNA gene sequence. The phylogenetic analysis indicated a higher evolutionary rate for the hsp60 gene sequence than the 16S rRNA gene sequence, especially in the genera Porphyromonas and Prevotella. This study suggests that the hsp60 gene is a useful alternative phylogenetic marker for the identification and classification of a broad range of Gram-negative anaerobic rods.