Prevotella, a new genus to include Bacteroides melaninogenicus and related species formerly classified in the genus Bacteroides.

It was recently proposed that the genus Bacteroides should be restricted to Bacteroides fragilis (the type species) and closely related organisms (viz., B. caccae, B. distasonis, B. eggerthii, B. merdae, B. ovatus, B. stercoris, B. thetaiotaomicron, B. uniformis, and B. vulgatus). By contrast, the moderately saccharolytic, predominantly oral Bacteroides species, which include B. melaninogenicus, B. oralis, and related species, form a phenotypically and phylogenetically coherent group of species which differ so significantly from the emended description of the genus Bacteroides that they should not be classified in the same genus. Therefore, we formally propose that these species be reclassified in a new genus, Prevotella. The type species is Prevotella melaninogenica.