The increase in the ratios of Bifidobacterium in the rat cecum by the intake of susabinori, Porphyra yezoensis, has been demonstrated. In the present study, we examined in vitro the ability of various intestinal bacteria to Ferment polysaccharides (xylan/mannan, porphylan, and floridean starch) extracted from susabinori, and the effects of these polysaccharides on the microfiora and metabolic products in the cecum of rats. Both xylan/mannan and porphylan were fermented by a few strains of intestinal bacteria, and floridean starch was fermented by many intestinal bacteria, except for Eubacterium. The cecum microfeora of rats was changed by the administration of xylan/mannan or porphylan added to diets and the number of Bifidobaterium increased by xylan/mannan. On the other hand, by administrating 1.0% porphylan, the total viable count, particularly that of Bifidobacterium, decreased. The pH of the cecum contents dropped by xylan/mannan or porphylan. Microflora and metabolic products were not significa-ntly changed by floridean starch. These results suggest that dietary fiber of susabinori influences the intestinal environment and each constituent dietary fiber shows a different function.
