Streptococcusdentiloxodontae 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 2404T, 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 2404T was related most closely to Streptococcus saliviloxodontae NUM 6306T with 95.8 % 16S rRNA gene sequence similarity, but the phylogenetic tree reconstructed based on the 16S rRNA gene sequence showed that NUM 2404T clustered with Streptococcus mutans NCTC 10449T and Streptococcus troglodytae TKU 31T. Comparative sequence analysis based on two housekeeping genes, groEL, which encodes the 60 kDa heat-shock protein, and rpoB, encoding the β subunit of RNA polymerase, of NUM 2404T indicated that it was most closely related to those of Streptococcus orisratti A63T and Streptococcus sobrinus ATCC 33478T 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 2404T (=JCM 19284T=DSM 27381T).