Actinomyces howellii, a New Species from the Dental Plaque of Dairy Cattle

Five strains of actinomyces isolated from the dental plaque of cattle were assigned presumptively to the genus Actinomyces on the basis of Gram staining, colonial and cellular morphology, fermentation reactions, and acid end products of metabolism. This assignment was confirmed by the molar composition of peptidoglycans. The isolates formed a homogeneous group on the basis of the sodium dodecyl sulfatepolyacrylamide electrophoresis patterns of their polypeptides, their cell wall carbohydrate constituents, and their deoxyribonucleic acid mean base compositions. They were also clearly related as determined by deoxyribonucleic acid-deoxyribonucleic acid homology, which distinguished them from strains of Actinomyces naeslundii, Actinomyces viscosus, and “Actinomyces denticolens.” A new taxon, Actinomyces howellii, is proposed for these strains, the type strain of which is strain NCTC 11636.