PHENOTYPIC CHARACTERIZATION OF HUMAN AND ANIMAL BIOTYPES WITHIN THE SPECIES PORPHYROMONAS-GINGIVALIS

Ninty-nine strains of Gram-negative black-pigmented anaerobic rods, gr own on Todd-Hewitt blood agar plates, were identified and characterize d according to a typing scheme including UV fluorescence, catalase, tr ypsin-like and haemagglutinating activities, biochemical tests with th e ATB 32A kit, and gas-liquid chromatography. To determine the taxonom ic position of the Porphyromonas gingivalis biotypes, 68 strains (31 o f human origin and 37 of animal origin) were compared to 31 strains of closely related species or of uncertain generic status. Most animal s trains were isolated in our laboratory by subculturing samples from th e oral cavity of five mammalian species (bear, cat, coyote, dog and wo lf). Those strains differed from human P. gingivalis strains in that t hey were positive for catalase, beta-galactosidase and glutamyl-glutam ic acid arylamidase; from Bacteroides macacae by more rapid pigmentati on, positive haemagglutination, failure to produce propionic acid, and negative alpha-galactosidase; and from Bacteroides salivosus by more rapid pigmentation, positive haemagglutination and failure to produce propionic acid. These data demonstrate that phenotypic heterogeneity w ithin the taxon P. gingivalis can be resolved into two biotypes, each corresponding to a human source or an animal source.