A species of anaerobic, Gram-negative, rod shaped bacteria assigned to the phylum Bacteroidetes. This species is non-motile, non-spore-forming, produces a tan to buff pigment on blood agar, fluoresces under UV (365 nm) light, sucrose, lactose, and beta-N-acetyl-glucosaminidase positive, but xylose arabinose, cellobiose, rhamnose, salicin, indole, esculin hydrolysis beta-glucosidase, and glycine aminopeptidase negative. P. melaninogenica is part of the normal human oral and vaginal flora, but can also be an opportunistic pathogen causing infections in both humans and animals.

A species of gram-negative, anaerobic, rod-shaped bacteria originally classified within the BACTEROIDES genus. This bacterium has been isolated from the mouth, urine, feces, and infections of the mouth, soft tissue, respiratory tract, urogenital tract, and intestinal tract. It is pathogenic, but usually in association with other kinds of organisms.

Any bacterial organism that can be assigned to the species Prevotella melaninogenica.