Prevotella bryantii, P. ruminicola and Bacteroides Strains

Abstract

Representatives of the Bacteroides/Flavobacterium/Cytophaga phylum of Gram-negative eubacteria are normally among the most numerous inhabitants of the rumen and of the human colon. Strains formerly regarded as Bacteroides ruminicola, isolated from the rumen and from the pig caecum, are genetically diverse and have now been reclassified into four species belonging to the genus Prevotella: P. ruminicola,P. bryantii, P. brevis and P. albensis (Avgustin et al. 1997, Shah and Collins 1990). Based on 16rDNA sequencing, the rumen Prevotella spp. belong to a broad cluster that is distinct from human colonic Bacteroides spp. (Avgustin et al. 1994). There is evidence that at least some plasmid replicons and marker genes can function in representatives of both groups, but replicons and marker genes derived from E. coli plasmids are seldom if ever found to function in Bacteroides/Prevotella spp. (Salyers and Shoemaker 1997). Human colonic Bacteroides and rumen Prevotella species are thought to play important roles in the metabolism of starch, protein, peptides, hemicellulose and pectin while human colonic Bacteroides spp. also metabolise host-derived polysaccharides (Salyers 1984). The phylum also contains opportunistic pathogens such as B. fragilis (Salyers 1984, Shah 1992).