Strain 28462T, which had Gram-stain-positive, catalase-negative coccus-shaped cells, was isolated from a routine tracheal sample from a 3 year old thoroughbred horse. 16S rRNA gene sequence analysis revealed it to be most closely related to, but distinct from, Streptococcus henryi (95.7 % identity), Streptococcusplurextorum (95.8 %), Streptococcusporci (96.4 %) and Streptococcus caprae (95.1 %). Similarity values derived from sequences from sodA and rpoB genes were consistent with strain 28462T belonging to a species distinct from these four streptococci. At the whole genome level, strain 28462T had an average nucleotide identity value <95 % and an inferred DNA-DNA hybridization value <70 % when compared to S. henryi, Streptococcus. plurextorum and S. porci with no S. caprae genome sequence being available. Finally, various phenotypic characteristics distinguish strain 28462T from each of these species. Based on the genotypic and phenotypic results, it is proposed that strain 28462T is a novel species, with the name Streptococcus hillyeri sp. nov. The type strain is 28462T (=DSM 107591T=CCUG 72762T).
Keywords: Streptococcus; equine; new taxon; veterinary microbiology.