Summary auto-generated
This study describes the characterization and identification of a previously unknown bacterium isolated from vaginal discharge in a horse. Using polyphasic taxonomic methods, researchers identified the organism as a novel species within the genus Arcanobacterium. The bacterium was a Gram-positive, facultatively anaerobic, diphtheroid-shaped organism. Through 16S rRNA gene sequencing, scientists determined that the isolate showed 94.8-95.7% sequence similarity to existing Arcanobacterium species, with the closest relative being Arcanobacterium phocae at 95.7% similarity. The 4.3% sequence divergence from the nearest species exceeded the 3% threshold for species delineation. Biochemical profiling using API systems further distinguished this organism from other Arcanobacterium species through unique enzyme production patterns and fermentation characteristics, including hippurate hydrolysis and specific acid production profiles. Based on these phylogenetic and phenotypic findings, the authors propose classification as a new species, Arcanobacterium hippocoleae sp. nov., with the type strain designated CCUG 44697T. The species name reflects its isolation source: the vagina of a horse.
Key findings
- A novel Arcanobacterium species, A. hippocoleae, was isolated from horse vaginal discharge and characterized through polyphasic taxonomy
- 16S rRNA gene sequencing showed 4.3% divergence from the closest relative A. phocae, exceeding the 3% threshold for species designation
- Biochemical testing revealed distinctive enzyme production patterns and fermentation profiles distinguishing A. hippocoleae from all other Arcanobacterium species
- The organism was Gram-positive, facultatively anaerobic, and catalase-negative, typical of the genus Arcanobacterium
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Abstract
A polyphasic taxonomic study was performed on a previously unidentified Gram-positive, facultatively anaerobic, diphtheroid-shaped organism isolated from a vaginal discharge of a horse. Comparative 16S rRNA gene sequencing demonstrated that the strain was a member of the genus Arcanobacterium, but sequence divergence values of >4% with described species of this genus (viz: Arcanobacterium haemolyticum, Arcanobacterium bernardiae, Arcanobacterium phocae, Arcanobacterium pluranimalium and Arcanobacterium pyogenes) demonstrated that the isolate represented a novel species. The unknown bacterium was readily distinguished from other Arcanobacterium species by biochemical tests. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Arcanobacterium hippocoleae sp. nov. The type strain of A. hippocoleae is CCUG 44697(T) (=CIP 106850(T)).