Streptococcus hillyeri sp. nov., isolated from equine trachea.

The research article discusses the identification of a new species of bacterium, Streptococcus hillyeri, which was isolated from an equine trachea sample.

Isolation of Strain 28462T

• Strain 28462T was isolated from a sample obtained from a 3-year-old Thoroughbred horse’s trachea during a regular check.
• The strain showed positive for Gram staining, which suggests the presence of peptidoglycan in the bacterial cell wall, and coccus-shaped cells were found implying it belongs to Streptococcus genus.
• The strain was found to be catalase-negative, meaning it doesn’t produce the enzyme that catalyzes the decomposition of hydrogen peroxide.

Gene Sequence Analysis

• 16S rRNA gene sequence analysis revealed that the strain was related to, but unique from, several identified species of Streptococcus including S. henryi (95.7% identity), S. plurextorum (95.8%), S. porci (96.4%), and S. caprae (95.1%).
• Further gene sequence analysis of the sodA and rpoB genes, also supported the distinct nature of strain 28462T from the aforementioned species.

Whole Genome Analysis

• At the whole genome level, strain 28462T shows an average nucleotide identity value of less than 95%, and an inferred DNA-DNA hybridization value less than 70% when compared to S. henryi, S. plurextorum and S. porci.
• Unfortunately, there was no S. caprae genome sequence available for comparison.

Phenotypic Characteristics

• Not only genotypically, but various phenotypic characteristics also set strain 28462T apart from the compared species.

Conclusion

• Given the distict genotypic and phenotypic results, strain 28462T is proposed to be a novel species of Streptococcus, named Streptococcus hillyeri.
• The type strain is given as 28462T (=DSM 107591T=CCUG 72762T).