Tomohiko Fujisawa

Effect of apple intake on fecal microbiota and metabolites in humans

The effects of apple intake on the fecal flora, water content, pH, and metabolic activities in eight healthy volunteers and the utilization of apple pectin in vitro were investigated. Although several isolates of Bifidobacterium, Lactobacillus, Enterococcus, and the Bacteroides fragilis group utilized apple pectin, most isolates of Escherichia coli, Collinsela aerofaciense, Eubacterium limosum, and Clostridium perfringens could not. When fecal samples from healthy adults were incubated in liquid broth with apple pectin present or absent, the numbers of Bifidobacterium and Lactobacillus in the former were higher than those in the later. After the intake of apples (2 apples a day for 2 weeks) by eight healthy adult humans, the number of bifidobacteria in feces increased (pxa0<xa00.05 on day 7 and pxa0<xa00.01 on day 14 of the intake period), and the numbers of Lactobacillus and Streptococcus including Enterococcus tended to increase. However, lecithinase-positive clostridia, including C. perfringens, decreased (pxa0<xa00.05), and Enterobacteriaceae and Pseudomonas tended to decrease. Moreover, the concentrations of fecal acetic acid tended to increase on apple intake. The fecal ammonia concentration showed a tendency to reduce and fecal sulfide decreased (pxa0<xa00.05) on apple intake. These findings indicate that apple consumption is related to an improved intestinal environment, and apple pectin is one of the effective apple components improving the fecal environment.

Safety evaluation of probiotic bifidobacteria by analysis of mucin degradation activity and translocation ability.

Although probiotic-containing nutrient formulas for infants and toddlers have become very popular, some adverse effects related to translocation of probiotic strains have been reported. We assessed the safety of probiotic bifidobacteria that have been used in clinical investigations and proven to have beneficial effects, by analyzing mucin degradation activity and translocation ability. Mucin degradation activities of three probiotic bifidobacteria strains; Bifidobacterium longum BB536, Bifidobacterium breve M-16V and Bifidobacterium infantis M-63, were evaluated by three in vitro tests comprising growth in liquid medium, SDS-PAGE analysis of degraded mucin residues, and degradation assay in Petri dish. All test strains and control type strains failed to grow in the liquid medium containing mucin as the only carbon source, although good growth was obtained from fecal sample. In the SDS-PAGE analyses of mucin residues and observation of mucinolytic zone in agar plate, the three test strains also showed no mucin degradation activity as the type strains, although fecal sample yielded positive results. In another study, a high dose of B. longum BB536 was administered orally to conventional mice to examine the translocation ability. No translocation into blood, liver, spleen, kidney and mesenteric lymph nodes was observed and no disturbance of epithelial cells and mucosal layer in the ileum, cecum and colon was detected, indicating that the test strain had no translocation ability and induced no damage to intestinal surface. These results resolve the concern about bacterial translocation when using bifidobacteria strains as probiotics, which have been tested in various clinical trials, supporting the continuous use of these probiotic strains without anxiety.

A taxonomic study on erysipelothrix by DNA-DNA hybridization experiments with numerous strains isolated from extensive origins.

The purpose of this study was to clarify the taxonomic relationship between all the serovars and species of the genus Erysipelothrix by performing DNA‐DNA hybridization experiments, the customary criterion for separation of bacterial genospecies. A total of 93 strains were isolated from a wide variety of sources, including pigs affected with acute or chronic erysipelas, other diseased animals, healthy animals, fish, retail meats, and environmental materials from throughout the world during the period 1958 to 1996. The present data on phenotypic characterization and DNA relatedness values demonstrate that 24 strains (96%) of E. tonsillarum are avirulent for swine, whereas 39 strains (66%) of genomic E. rhusiopathiae induced generalized or local urticarial lesion in swine after intradermal inoculation. This observation suggests that genomic E. tonsillarum has little etiological significance. Three minor groups contained several strains which exhibited minimal association with each type strain of E. rhusiopathiae and E. tonsillarum. In conclusion, it was confirmed that members of the E. rhusiopathiae and E. tonsillarum groups resemble each other in regard to many phenotypic characteristics, but differ in their ability to produce acid from saccharose and in their pathogenicity for swine. The genus Erysipelothrix certainly contains two main species: E. rhusiopathiae and E. tonsillarum.

Consumption of partially hydrolysed guar gum stimulates Bifidobacteria and butyrate-producing bacteria in the human large intestine

Partially hydrolysed guar gum (PHGG) is a water-soluble dietary fibre that is non-digestible in the upper gastrointestinal tract. It is believed that PHGG benefits the health of hosts by altering the colonic microbiota and stimulating short-chain fatty acid (SCFA) production. However, it remains unclear which bacteria ferment PHGG in the human large intestine. In this study, the effect of PHGG on faecal bacteria was analysed to specify the bacteria that contribute to the fermentation of PHGG in the human large intestine. Ten healthy volunteers consumed PHGG (6 g/day) for 2 weeks. Faeces were collected at 2 weeks prior to consumption, at the end of 2 weeks of consumption, and 2 weeks after consumption of PHGG. Bacterial DNA was extracted from these collected faeces and subjected to real-time PCR using bacterial group- or species-specific primers. The copy number of the butyryl-CoA CoA-transferase gene and the 16S rRNA gene copy numbers of Bifidobacterium, the Clostridium coccoides group, the Roseburia/ Eubacterium rectale group, Eubacterium hallii, and butyrate-producing bacterium strain SS2/1 were significantly increased by the intake of PHGG. Other bacteria and bacterial groups were not significantly influenced by the intake of PHGG. It was believed that the Roseburia/E. rectale group bacteria, Bifidobacterium, the lactate-utilising, butyrate-producing bacteria, E. hallii and bacterium strain SS2/1, would contribute to the fermentation of PHGG in the human large intestine. PHGG may benefit health by stimulating Bifidobacterium and butyrate-producing bacteria in the human large intestine.

Effects of non-fermented and fermented soybean milk intake on faecal microbiota and faecal metabolites in humans

The effects of non-fermented soybean milk (NFSM) and fermented soybean milk (FSM) intake on the faecal microbiota and metabolic activities in 10 healthy volunteers were investigated. Soybean oligosaccharides, raffinose and stachyose were utilized by bifidobacteria except for Bifidobacterium bifidum, but most strains of Escherichia coli and Clostridium perfringens could not use them. During the dietary administration of FSM, the number of bifidobacteria and lactobacilli in the faeces increased (p < 0.05), and clostridia decreased (p < 0.05). Moreover, the concentrations of faecal sulphide were decreased (p < 0.01) in the intake of FSM. During the dietary administration of NFSM, the number of bifidobacteria tended to increase. These results indicate that the consumption of soybean milk, especially FSM, is related to improvement of the intestinal environment.

Colonization of segmented filamentous bacteria and its interaction with the luminal IgA level in conventional mice.

Segmented filamentous bacteria (SFB) colonize in the ileum. They promote the development of intraepithelial lymphocytes and immunoglobulin A (IgA)-producing cells in the small intestine. In SFB-monoassociated mice, changes in SFB colonization of the small intestine were related to the level of IgA derived from maternal milk during the suckling period and self-produced in the small intestine after weaning. In this study, we investigated whether or not maternal and neonatal IgA influence the colonization of SFB in conventional mice from 18 to 105 days old. The pups were forcedly weaned at 20 days old. SFB could be detected in the distal small intestine after day 22, and their number rapidly reached a maximum on day 28. Thereafter, they gradually declined to one-fourth of the maximum level. The lowest concentrations of IgA in the small intestinal and cecal contents were detected on day 22. Thereafter, they increased as the age of the mice increased. The expression of the polymeric immunoglobulin receptor gene in the distal small intestine increased after weaning. These results suggested that the colonization of SFB in the pre-weaning and post-weaning periods might be prevented with IgA derived from maternal milk and self-produced IgA, respectively.

Anti-tumor activity of heat-killed Lactobacillus plantarum BF-LP284 on Meth-A tumor cells in BALB/c mice

Abstract Probiotics exert numerous effects on human well-being. Here, heat-killed Lactobacillus plantarum BF-LP284 (H-Lp) was isolated as a potent immuno-modulator among 15 strains of lactobacilli in terms of TNF-α induction ability in peritoneal macrophages. In vitro TNF-α and IFN-γ induction in Peyer’s patch (PP) cells was higher when incubated with H-Lp than with live L. plantarum BF-LP284 (L-Lp). Suppression of syngeneic Meth-A tumors in a murine model by oral administration of H-Lp was also greater than that of L-Lp and of controls. H-Lp stimulated IFN-γ production in spleen cells, which displayed inhibited tumor growth in Winn assays when treated with H-Lp. Moreover, H-Lp increased the ratio of CD3+u2009cells among peripheral blood mononuclear cells in Meth-A tumor-bearing mice, suggesting an H-Lp-mediated anti-tumor mechanism whereby immune cells that are activated by H-Lp in PP and acquire anti-tumor activity in the spleen migrate to tumor sites through lymphocyte homing to inhibit tumor growth.

Detection of antibiotic resistance genes in the feces of young adult Japanese

Antibiotic resistance genes in the feces of healthy young adult Japanese were analyzed with polymerase chain reaction using specific primers. Antibiotic resistance genes against macrolides (ermB, ermF, ermX, and mefA/E), tetracyclines (tetW, tetQ, tetO, and tetX), β-lactam antibiotics (blaTEM), and streptomycin (aadE) were detected in more than 50% of subjects. These antibiotic resistance genes are likely widespread in the large intestinal bacteria of young adult Japanese.

The effect of soymilk intake on the fecal microbiota, particularly Bifidobacterium species, and intestinal environment of healthy adults: a pilot study

The influence of soymilk on the fecal microbiota, particularly Bifidobacterium species, and metabolic activities were investigated in eight healthy adult humans. During the soymilk intake period, the number of bifidobacteria in feces was significantly higher (p<0.05) on day 14 of the soymilk intake period than before the intake period, whereas that of Enterobacteriaceae was significantly lower (p<0.05) on days 7 and 14 of the soymilk intake period than before the intake period. In an investigation of Bifidobacterium at the species or group level, the numbers of all species and groups studied slightly increased during the soymilk intake period. These results show that the intake of soymilk may contribute to improving the intestinal environment.