The ruminants can utilize the breeding of forages by the microbial degradation of plant cell wall material in the rumen. To improve the efficiency of utilization of forages by rumen, the development of molecular breeding of rumen bacteria having a high digestible ability of cellulose would be valuable. For major rumen bacteria, we constructed new host vector systems. And molecular ecology techniques based on 16S rRNA sequences were used to descriptive of the microbial ecology of the rumen of ruminant animals.

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To investigate the survival of probiotic bacteria, Bifidobacterium breve strain Yakult, in the gastrointestinal tract, we have developed a selective medium and introduced randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) technique to isolate and identify this strain. The survival of the strain was determined by its fecal recovery after 3 days of intake of fermented milk containing the strain. Volunteers of 8 healthy male adults ingested 100 ml of the fermented milk (Yakult MilMil S) after lunch for 3 days. Stools of passed early in the morning on day 1 (the first day of dairy product intake) and those passed in the morning on day 4 were sampled. Each stool specimens were cultured on selectivemedium to quantitatively determine the fecal recovery of the strain. Colonies of B. breve strain Yakult grown on the selective medium were identified by RAPD-PCR technique. B. breve strain Yakult wasgenerally not isolated at a high number from stool specimens obtained before the intake of the fermented milk containing this strain. After 3 days intake of the fermented milk products, B. breve strain Yakult was detected from all stool specimens, with the respective mean number of live bacteria per gram of feces being 10^7.18±0.83. We propose to use RAPD-PCR analysis as a rapid and reliable test for differentiation between administered probiotic strain and other indigenous intestinal bacteria. The results of the present study confirm that B. breve strain Yakult administered in fermented milk products can survive in the gastrointestinal tract.

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The ability to survive of Lactobacillus plantarum ONC141 strain in the gastrointestinal tract andthe effect of administration of L. plantarum fermented milk on fecal microflora in human were studied. Six healthy subjects consumed 200 ml of fermented milk containing 5.3×10⁸ CFU of L. plantarum ONC141 strain per ml for seven days. L. plantarum ONC141 strain was enumerated in fresh feces before (day 0) and after ingestion (days 1, 2, 4, 7). L. plantarum ONC141 strain was not detected at day 0, but averaged 10⁷-10⁸CFU per gram feces for the other days. Twenty-one healthy subjects were divided into 2 groups that consumed for 4 weeks either 300 ml of fermented milk containing 7.1×10⁷CFU of L. plantarum ONC141 strain per ml (11 subjects) or 300 ml of commercial cow's milk (10 subjects). Fecal samples were collected before and after the ingestion period and the fecal microflora was analyzed. The numbers of fecal lactobacilli and bifidobacteria increased significantly in individuals given fermented milk with L. plantarum ONC141 strain and were significantly higher than those detected in individuals fed commercial cow's milk. In addition, thepercentage of bifidobacteria was remarkably increased by ingestion of fermented milk (from 21% to 44% of total counts). These results demonstrate that L. plantarum ONC141 strain in the fermented milk can survive in the human gastrointestinal tract, and alter the composition of the fecal microflora, in a manner consistent with providing beneficial effects for human health.

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Fermented milk prepared with Lactobacillus plantarum ONC141 strain was administered at 300 ml/day for 3 weeks to 16 constipated adults (average age 40.3 years) whose defecation frequency is under 4 times per week, and its effect on defecation frequency, fecal characteristics and fecal microflora were investigated. The defecation frequency was significantly increased by administration of the fermented milk. This result indicate that the administration of the fermented milk is effective to improve the defecation frequency. Improvement of fecal hardness, fecal shape, fecal color and feeling of defecationwere observed after intake of the fermented milk. The number and ratio of bifidobacteria to total bacteria were increased, whereas the number of Enterobacteriaceae were decreased. Fecal putrefactive metabolites and fecal pH did not change after intake of the fermented milk. Clinical symptom caused by the fermented milk ingestion were not observed. These results indicate that the continuous intake of the fermented milk prepared with L. plantarum improves defecation frequency, fecal characteristics and fecal microflora.

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We determined the effects of a dried brewer's yeast tablet and a brewer's yeast drink, whichcontained brewer's yeast suspension that was fermented by Lactobacillus rhamnosus SN88 (final pH 4.07) and sterilized, on the defecation of twenty-five human volunteers aged from 22 to 57 years old (average 33.3 years old) who showed signs of constipation. For three weeks, one group of twelve subjects was administered with 25 yeast tablets containing 3.75g dried yeast per day ‹tablets group›, and another group of thirteen subjects was administered one can of the yeast drink (160g per can), which contained the same amount of dried yeast as 25 tablets ‹drink group›. The tablets group also drank the same volume of water as the yeast drink when they took the tablets. The pre- and post-administration periods lasted 2 weeks, during which the subjects did not take any test samples. They were also instructed not to consume any other fermented foods, oligosaccharides, “natto, ” vegetable juice or drugs, as these edibles could have influenced the defecation of the subjects throughout the study period. The applicable cases for analysis after the intake period were 9 for the tablets group and 8 for the drink group. Significant increases in defecation frequency and in the amounts of defecation as well as improvements in feeling after defecation and in the weekly subjective constipation status were observed during the intake period in the drink. There were also changes in shape and hardness of feces, but these were not significant. Those improvements in defecation returned to the same level before the intake period. Although some improvement in defecation was also shown in the tablets group, there was no significant difference. Accordingly, the brewer's yeast drink fermented by lactic acid bacteria proved to be useful for improving the defecation of people with constipation.

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