Streptococcus cuniculi sp. nov., isolated from the respiratory tract of wild rabbits

Abstract

Biochemical and molecular genetic studies were performed on four unknown Gram-stain-positive, catalase-negative, coccus-shaped organisms isolated from tonsils (n = 3) and nasal samples (n = 1) of four wild rabbits. The micro-organism was identified as a streptococcal species based on its cellular morphological and biochemical tests. Comparative 16S rRNA gene sequencing confirmed its identification as a member of the genus Streptococcus , but the organism did not correspond to any recognized species of this genus. The closest phylogenetic relative of the unknown cocci from wild rabbits was Streptococcus acidominimus NCIMB 702025T (97.9 % 16S rRNA gene sequence similarity). rpoB and sodA sequence analysis of the novel isolate showed interspecies divergence of 16.2 % and 20.3 %, respectively, from the type strain of its closest 16S rRNA gene phylogenetic relative, S. acidominimus . The novel bacterial isolate could be distinguished from the type strain of S. acidominimus by several biochemical characteristics, such as the production of esterase C4, acid phosphatase and naphthol-AS-BI-phosphohydrolase and acidification of different sugars. Based on both phenotypic and phylogenetic findings, it is proposed that the unknown bacterium be classified as a novel species of the genus Streptococcus , Streptococcus cuniculi sp. nov. The type strain is NED12-00049-6BT ( = CECT 8498T = CCUG 65085T).