Actinomyces capricornis sp. nov., isolated from the oral cavity of a Japanese serow

A novel Gram-positive, facultatively anaerobic, rod-shaped, nonspore forming, nonmotile organism was isolated from a Japanese serow oral cavity. Designated strain MAS-1^T, it is most closely related to Actinomyces bowdenii DSM 15435^T, with which it shares 98.07% sequence homology in the 16S ribosomal RNA gene. The primarily detected cellular fatty acids in strain MAS-1^T were C_16:0 and C_18:1w9c. The predominant respiratory quinone was MK-9 (H₄). The major polar lipids were phosphatidylcholines, phosphatidylinositols, and glycophospholipids. The genomic DNA GC content of the isolate was 71.3 mol%. The digital DNA–DNA hybridization and average nucleotide identity values between MAS-1^T and its related species were 23.5%–39.5% and 82.11%–91.01%, respectively, which were below the threshold (70% and 95%, respectively) for species delineation, indicating that strain MAS-1^T represents a novel species. Strain MAS-1^T can be differentiated from A. bowdenii by their reactions to naphthol-AS-BI-phosphohydrolase, α-galactosidase, β-galactosidase, and N-acetyl-β-glucosaminidase, as well as differing acid production from glycogen. Based on the results of genotypic, phenotypic, and biochemical analyses, herein it is proposed that the identified bacteria can be classified as a novel species, Actinomyces capricornis sp. nov., strain MAS-1^T (=JCM 34236^T = DSM 111732^T).