Streptococcus dentiloxodontae sp nov., isolated from the oral cavity of elephants

A Gram-stain-positive, catalase-negative, coccus-shaped organism was isolated from oral cavity samples collected from healthy elephants. The isolated strain, NUM 2404(T), was tentatively identified as a streptococcal species based on the results of biochemical tests. Although a comparative 16S rRNA gene sequence analysis suggested the classification of this organism into the genus Streptococcus, it did not correspond to any recognized species of the genus. Strain NUM 2404(T) was related most closely to Streptococcus saliviloxodontae NUM 6306(T) with 95.8% 16S rRNA gene sequence similarity, but the phylogenetic tree reconstructed based on the 16S rRNA gene sequence showed that NUM 2404(T) clustered with Streptococcus mutans NCTC 10449(T) and Streptococcus troglodytae TKU 31(T). Comparative sequence analysis based on two housekeeping genes, groEL, which encodes the 60 kDa heat-shock protein, and rpoB, encoding the beta subunit of RNA polymerase, of NUM 2404(T) indicated that it was most closely related to those of Streptococcus orisratti A63(T) and Streptococcus sobrinus ATCC 33478(T) with 82.7 and 85.1% sequence similarities, respectively. On the basis of genotypic and phenotypic differences, it is proposed that the novel isolate be classified in the genus Streptococcus as representative of a novel species, Streptococcus dentiloxodontae sp. nov. The type strain is NUM 2404(T) (=JCM 19284(T) =DSM 27381(T)).