We have previously reported the absence of cholic acid 7α-dehydroxylase activity in several industrial stock cultures as well as intestinal strains of lactic acid bacteria. In this study, the presence of 7α-dehydroxylase activity in the bile acids of human intestinalBifidobacteriumandLactobacillusstrains was investigated. Twelve strains ofBifidobacteriumsp. and 10 strains of Lactobacillus sp. were freshly isolated from six healthy human subjects and tested for their ability to produce deoxycholic acid from cholic acid. The production of deoxycholic acid was quantitatively measured by HPLC analysis. In growing cultures, more than 90% of the 150μg/ml of cholic acid was transformed to deoxycholic acid by a positive control strain, Eubacterium lentum-like strain c-25, after 7 days of anaerobic incubation. However, none of the test strains showed the production of deoxycholic acid as growing cultures. These results indicate, together with the results of our previous study, that strains ofBifidobacteriumandLactobacillusregardless of their origin or subculture, lack bile acid 7α-dehydroxylase.

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The effects of beet dietary fiber (BDF) on intestinal flora and intestinal metabolic products were determined in healthy humans and rats. The major compositions of fecal flora in seven volunteers didn't change during the intake of BDF (10g/day) for 21 days. While a significant increase in the frequency of evacuation and fecal water content, a significant decrease in fecal putrefactive products, such as the concentrations of each ammonia and indole, were observed in humans during BDF intake. In the animals given a purified diet supplemented with 10% BDF, the number of strict anaerobic bacteria was unchanged, but that of the facultative anaerobes such as enterobacteriaceae and streptococci significantly decreased. The cecal amount of short-chain fatty acids in the animals significantly increased, in particular ton- butyric acid. In the cultures supplemented with human feces or rat cecal contents with BDF, a marked increase of acetic acid and a slight increase ofn-butyric acid were also observed. Finally, BDF intake induced a slight change in the compositions of the intestinal flora in humans and rats and useful changes in intestinal metabolic products.

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Fermented milk prepared withLactobacillus acidophilusSBT 2062, Bifidobacterium longumSBT 2928, Streptococcus thermophilusSBT 1035 andLactobacillus delbrueckiisubsp.bulgaricusSBT 0164 (containing 6.5×10⁶∼1.0×10⁷cfu/g ofL. acidophilusSBT 2062 and 6.0×10⁶∼1.0×10⁷cfu/g ofB. longum SBT 2928) was administered at 100 g/day for 1 week to 79 healthy adults (39 men, 40 women, average age 36.7 years). The fecal microflora of 9 adults (3 men, 6 women, average age 27.8 years) selected from the 79 healthy adults were studied. An increase in defecation frequency by the persons whose frequency was relatively low, improvement of fecal shape, change of fecal color from dark brown to yellowish brown, and decrease in fecal odor were observed after administration. The number and ratio of bifidobacteria to total bacteria were significantly increased, whereas the number of clostridia (lecithinase positive) and ratio of bacteroidaceae to total bacteria were decreased after administration. In addition, fecal pH decreased after administration.

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