Prevotella melaninogenica is a species of bacterium in the normal microbiota of the upper respiratory tract. It is an important human pathogen in various anaerobic infections, often mixed with other aerobic and anaerobic bacteria. P. melaninogenica is an anaerobic, Gram-negative rod, named for its black colonies, and black pigment. Prevotella melaninogenica is associated with hypertension together with Campylobacter rectus and Veillonella parvula. Source: Wikipedia (en)