Isolation and characterization of Streptococcus respiraculi sp. nov. from Marmota himalayana (Himalayan marmot) respiratory tract.

Two bacterial strains were individually isolated from Marmota himalayana respiratory tracts; the animals were from the Tibet-Qinghai Plateau, PR China. The isolates were Gram-stain-positive, catalase-negative, coccus-shaped, chain-forming organisms. Analysis of 16S rRNA gene sequences indicated that the type strain HTS25 shared 98.0, 97.4, 97.2 and 97.1 % similarity with Streptococcus cuniculi, Streptococcus acidominimus, Streptococcus marmotae and Streptococcus himalayensis respectively. Sequence analysis of the sodA and rpoB genes indicated that HTS25 was closely related to S. marmotae (similarities of 94.7 and 91.4 % respectively). Analysis of groEL sequences showed interspecies similarity of 84.8 % between HTS25 and S. himalayensis. A whole-genome phylogenetic tree reconstructed from 81 core genes from the genomes of 17 members of the genus Streptococcus was used to validate that HTS25 forms a distinct subline from other recognized species of the genus Streptococcus. DNA-DNA hybridization of HTS25 showed a maximum estimated DNA reassociation value of 32.1 % to Streptococcus cuniculi CCUG 65085. On the basis of the results of phenotypic and phylogenetic analyses, we propose that the two isolates be classified as representing a novel species of the genus Streptococcus, named Streptococcus respiraculi sp. nov. The type strain is HTS25 (=DSM 101998=CGMCC 1.15531). The genome of Streptococcus respiraculi sp. nov. strain HTS25 (2 067 971 bp) contains 2001 genes with an average DNA G+C content of 42.7 mol%.