Studies of the Morpholoǵical, Physioloǵical, and Biochemical Characters of Actinomyces bovis Pine, L. and Howell, A. and Watson, Sarah J.,, 23, 403-424 (1960), doi = https://doi.org/10.1099/00221287-23-3-403, publicationName = Microbiology Society, issn = 1350-0872, abstract= SUMMARY: A study was made of 11 bovine strains of Actinomyces. These strains were compared with 15 human strains identified as Actinomyces israelii and Actinomyces naeslundii. Ten of the bovine strains constituted a homogeneous group identified as Actinomyces bovis. One of the bovine strains was identified as A. israelii. The characteristics of Actinomyces bovis were the following: it failed to form a true mycelium in vitro; it had less tendency than A. israelii and A. naeslundii to form mycelial elements in lesions in animals into which it was inoculated. Characteristically it formed two types of colonies when first isolated from animals and when maintained in culture. These colonies were: (1) a smooth glistening transparent microcolony having an entire or furred edge; (2) a raised, opaque, rough colony having an entire or furred edge. The microcolonies of A. bovis were very characteristic on brain heart infusion agar and were easily differentiated from the mycelial colonies of A. israelii and A. naeslundii. Variation of the morphology of the colonies occurred rapidly in vitro as a result of genetic change and the medium used. When large, on certain media, the colonies of either the rough or smooth variants were sometimes indistinguishable from colonies of A. israelii or A. naeslundii, but were easily distinguishable on brain heart infusion agar. A. bovis was a catalase negative anaerobe which did not hydrolyse gelatin or casein; but in contrast to A. israelii and A. naeslundii it hydrolysed starch rapidly and completely when tested with KI +12 solution. A. bovis produced acid but no gas from starch but did not form acid or gas from xylose, raffinose, and mannitol, and did not reduce nitrate to nitrite. A. israelii did not form acid or gas from starch; it usually produced acid but no gas from xylose and mannitol, and occasionally produced acid but no gas from raffinose; it reduced nitrate to nitrite sometimes. A. naeslundii produced no acid or gas from starch; it produced acid but no gas from raffinose but not from xylose or mannitol, and it reduced nitrate to nitrite., language=, type=