Effect of dietary fiber on a guinea pig intestinal anaerobe, Bacteroides ovatus

The purpose of this study was to determine the effect of fibrous plant components on the growth of intestinal bacteria. An anaerobe was isolated from the guinea pig cecum and identified as Bacteroides ovatus. The organism was grown anaerobically in two types of media and shown to require hemin or protoporphyrin IX. Treatment of the media with water-insoluble fractions of alfalfa, cabbage, spinach or wheat bran inhibited growth of the culture. Inhibition occurred whether the residue remained in the medium during culture growth or was removed before inoculation. A chelating resin also removed an essential component of the medium. Both treatments depleted the medium of hemin and addition of hemin restored growth and acid production. Treatment of the water-insoluble residues of alfalfa or cabbage with dilute NaOH decreased their inhibitory effects. This suggests that plant cell wall components possess unique and labile chemical properties. Dietary fiber may inhibit the growth of some anaerobic species in the lower intestinal tract by making hemin unavailable.