Genomic and phenotypic description of Streptococcus resistens sp. nov., Streptococcus buccae sp. nov. and Streptococcus mediterraneus sp. nov., three new members of the Streptococcus genus isolated from the human oral cavity

Abstract

Phenotypic, phylogenetic and genomic studies were carried out on three unidentified Gram-stain positive, facultative anaerobic, and cocci-shaped bacteria isolated from the human oral cavity. The 16S rRNA gene of strains Marseille-P5794 T , Marseille-P6264 T and Marseille-P7376 T exhibited a sequence identity of 99,41%, 99.67% and 97.88%, respectively with Streptococcus cristatus, their closest phylogenetic relative with standing in nomenclature. Moreover, the rpoB gene sequence of strains Marseille-P5794 T and Marseille-P6264 T shared a similarity level with 96.1%, and 95.9% with Streptococcus cristatus whereas strain Marseille-P7376 T shared a 93.98% identity with Streptococcus sanguinis. Whole genome comparison of strains Marseille-P5794 T , Marseille-P6264 T and Marseille-P7376 T with their phylogenetic neighbours were under the threshold values set to define new species using digital DNA-DNA hybridization and Orthologous Average Nucleotide Identity. The taxonogenomics analysis thus allowed the classification of these strains as new species within the Streptococcus genus named Streptoccocus resistens sp. nov. Strain Marseille-P5794 T (=CSUR P5794 = CECT9902), Streptococcus buccae sp. nov. Strain Marseille-P6264 T (=CSUR P6264 = CECT9910) and Streptococcus mediterraneus sp. nov. Strain Marseille-P7376 (=CSUR P7376 = CECT30035).