1. A genus of small anaerobic gram-negative nonmotile cocci and usually short rods that produce smooth, gray to black pigmented colonies the size of which varies with the species. In humans, they are found as part of the normal flora in the oropharynx, including gingival crevices, and in the vaginal and intestinal tracts. The type species is Porphyromonas asaccharolytica.
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