Summary auto-generated
Researchers isolated a previously unknown Gram-negative bacterium from three harbor porpoises (Phocoena phocoena) that stranded on the Scottish coast during 1995-1996. Biochemical and physiological characterization indicated the organism belonged to the family Pasteurellaceae. The bacteria were catalase-negative, oxidase-positive, non-motile rods that required added CO2 for growth and did not require X and V factors. 16S rRNA gene sequencing revealed the isolates formed a distinct subline within Pasteurellaceae, with the closest relative being Actinobacillus delphinicola, another species from sea mammals. However, a 3% sequence divergence distinguished the porpoise bacterium as a separate species. The three recovered strains exhibited genetic homogeneity and were isolated from various tissues including brain, lungs, spleen, liver, and blood, suggesting potential pathogenic significance. Based on phenotypic and phylogenetic analyses, the authors designated this novel bacterium as Actinobacillus scotiae sp. nov., assigning it to the genus Actinobacillus as a matter of convenience given phylogenetic complexity within the Pasteurellaceae family.
Key findings
- Actinobacillus scotiae sp. nov. is a new Gram-negative rod-shaped bacterium isolated from three stranded harbor porpoises in Scotland
- 16S rRNA sequencing showed A. scotiae forms a distinct species with 96.3% similarity to A. delphinicola and 3% sequence divergence, meeting species definition criteria
- The bacterium is catalase-negative, oxidase-positive, requires CO2 for growth, and produces acid from glucose, lactose, and mannose, distinguishing it from other Actinobacillus species
- A. scotiae and A. delphinicola are both isolated from cetaceans, representing marine-associated members of the Pasteurellaceae family
- The organisms were recovered from multiple tissues of infected porpoises, including brain, blood, and organ samples, indicating potential pathogenic importance
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Abstract
Phenotypic and phylogenetic studies were performed on a Gram-negative, rod-shaped bacterium isolated from three porpoises. Biochemical and physiological studies indicated that the bacterium was related to the family Pasteurellaceae. Comparative 16S rRNA gene sequencing studies confirmed these findings and demonstrated that the bacterium represents a hitherto unknown subline. The nearest phylogenetic relative of the unknown bacterium wasActinobacillus delphinicola, an organism also originating from sea mammals, although a sequence divergence of 3% demonstrated that the newly isolated bacterium is a distinct species. On the basis of the results of the phylogenetic analysis and phenotypic criteria, it is proposed that the bacterium should be classified as a new species, Actinobacillus scotiae sp. nov. The type strain of Actinobacillus scotiae sp. nov. is NCTC 12922T(= M2000/95/1T).