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 b 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).