Porphyromonas

**Definition:** A genus of gram-negative, anaerobic, nonsporeforming, nonmotile rods or coccobacilli. Organisms in this genus had originally been classified as members of the BACTEROIDES genus but overwhelming biochemical and chemical findings indicated the need to separate them from other Bacteroides species, and hence, this new genus was created.

**Tree numbers:** - B03.440.080.094.625 - B03.440.425.410.194.625