Summary auto-generated
This study describes the characterization and identification of Helcococcus ovis, a previously unknown Gram-positive, catalase-negative coccus isolated from sheep. Two strains were recovered from different sources: one from lung, liver, and spleen of a deceased Scottish sheep, and another from milk of a Spanish sheep with subclinical mastitis. Both isolates were facultatively anaerobic, non-hemolytic cocci that produced acid from glucose but not gas. Using polyphasic taxonomic methods including 16S rRNA gene sequencing, biochemical testing, and whole-cell protein analysis, researchers demonstrated that the unknown organism was phylogenetically distinct from the previously described Helcococcus kunzii, with approximately 96% sequence similarity and 4% sequence divergence. Biochemical differentiation tests clearly distinguished H. ovis from H. kunzii. The type strain CCUG 37441T has a G+C content of 29 mol%. Although both isolates were recovered alongside other potential pathogens, the clinical significance of H. ovis remains unclear.
Key findings
- Helcococcus ovis is a new Gram-positive, catalase-negative coccal species isolated from sheep with a type strain (CCUG 37441T) having 29 mol% G+C content
- 16S rRNA gene sequencing showed 100% similarity between the two isolates and 96% similarity to H. kunzii, supporting separate species status with 4% sequence divergence
- H. ovis is readily distinguished from H. kunzii by biochemical tests including acid production from lactose, pullulan, and trehalose, and differences in enzymatic activities
- Both isolates were recovered from sheep in mixed cultures with other organisms, but clinical significance could not be definitively established
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Abstract
Two strains of a hitherto undescribed Gram-positive, catalase-negative, facultatively anaerobic coccus isolated from sheep were characterized by phenotypic and molecular taxonomic methods. Comparative 16S rRNA gene sequencing studies demonstrated that the unknown strains were genealogically highly related and constitute a new line close to, but distinct from, Helcococcus kunzii. The unknown bacterium was readily distinguished from H. kunzii by biochemical tests and electrophoretic analysis of whole-cell proteins. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Helcococcus ovis sp. nov. The type strain of Helcococcus ovis is CCUG 37441T.