Tomoko Yaeshima

Morinaga Milk Industry Co., Ltd., Edo, Tōkyō, Japan

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Publications (57)88.43 Total impact

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    ABSTRACT: The effects of administration of bifidobacteria on the intestinal microbiota in low-birth-weight infants, and the transition of each strain of administered bifidobacteria were investigated. A single strain of Bifidobacterium breve M-16V (5×10(8); one-species group) or a mixture of three species composed of B. breve M-16V, Bifidobacterium longum subsp. infantis M-63 and Bifidobacterium longum subsp. longum BB536 (5×10(8) of each strain; three-species group) were administered daily for 6 weeks. Bifidobacterial administration significantly increased the detection rates and cell numbers of bifidobacteria in the feces (weeks 1-6). The proportion of bifidobacteria was significantly higher in the one-species group at weeks 1 to 4, and in the three-species group at weeks 1 to 6 compared with the control group. Furthermore, the proportion of bifidobacteria in the three-species group was significantly higher than that in the one-species group at weeks 1 and 6. The proportion of infants with bifidobacteria-predominant microbiota was significantly higher in the three-species group than in the control group during the test period. The detection rates of Clostridium were lower in the bifidobacteria-administered groups. The proportions of Enterobacteriaceae were significantly lower in the three-species group compared to the other groups (weeks 4 and 6). Among the three strains administered, B. breve M-16V and B. infantis M-63 were detected in 85% or more of the infants during the administration period, while B. longum BB536 was detected in 40% or less. Compared with administration of one species, administration of three species of bifidobacteria resulted in earlier formation of a bifidobacteria-predominant fecal microbiota and maintenance of this microbiota.
    No preview · Article · Aug 2013 · Anaerobe
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    ABSTRACT: The goal of this study was to establish a rapid assay for the specific detection of viable Cronobacter sakazakii in powdered infant formula (PIF). Samples were subjected to treatment multiple times with ethidium monoazide with a concentration gradient (gEMA) prior to PCR to discriminate viable from dead C. sakazakii cells. To improve the current detection limits, we developed a new buffer for direct quantitative real-time PCR (DqPCR) without DNA isolation. Using 17 PIF samples, our rapid assay was compared with the new U.S. Food and Drug Administration (FDA) method published in the Bacteriological Analytical Manual in 2012. Although both the new FDA method and our rapid assay, which consists of DqPCR combined with gEMA (gEMA-DqPCR), produced negative results for all 17 PIF samples, 5 of the 17 PIFs were positive by DqPCR when they were not treated with EMA. Furthermore, for PIF samples artificially contaminated with viable C. sakazakii, gEMA-DqPCR successfully detected between 1 and 9 CFU of viable C. sakazakii in 300 g of PIF within 9 h, including a 6-h preincubation. Our results indicate that multiple EMA treatments are required to avoid false-positive results due to the contamination of commercial PIF with dead or injured C. sakazakii cells. Our rapid assay may also improve the sensitivity of the screening portion required by the new FDA method published in the Bacteriological Analytical Manual in 2012.
    No preview · Article · Sep 2012 · Journal of food protection
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    ABSTRACT: Several studies have demonstrated that some strains of lactic acid bacteria (LAB) can elicit natural killer (NK) cell activities via interleukin-12 (IL-12) induction and protect against influenza virus (IFV) infection. LAB strains that strongly induce IL-12 are expected to be effective in protecting against IFV infection. In this study, we screened 85 strains for their ability to induce the in vitro production of IL-12, and Lactobacillus paracasei MoLac-1 most strongly induced IL-12. To examine the immunomodulating effects of MoLac-1, we have performed in vitro studies using murine splenocytes. Heat-killed MoLac-1 cells induced IL-12 and interferon-γ (IFN-γ) production by murine splenocytes. Experiments using splenocytes depleted of various cell populations indicated that macrophages might be a major source of MoLac-1-induced IL-12 secretion. Intracellular staining of IFN-γ suggested that MoLac-1 activated NK cells and induced IFN-γ production by NK cells in vitro. Oral administration of heat-killed MoLac-1 increased the proportion of NK cells in spleen, and ameliorated the symptoms of IFV infection in mice. These results suggest that heat-killed MoLac-1 has the potential to modulate innate immunity and is useful for alleviation of the symptoms of IFV infection.
    Preview · Article · Jul 2012 · FEMS Immunology & Medical Microbiology
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    ABSTRACT: Pasteurized milk is a complex food that contains various inhibitors of polymerase chain reaction (PCR) and may contain a large number of dead bacteria, depending on the milking conditions and environment. Ethidium monoazide bromide (EMA)-PCR is occasionally used to distinguish between viable and dead bacteria in foods other than pasteurized milk. EMA is a DNA-intercalating dye that selectively permeates the compromised cell membranes of dead bacteria and cleaves DNA. Usually, EMA-PCR techniques reduce the detection of dead bacteria by up to 3.5 logs compared with techniques that do not use EMA. However, this difference may still be insufficient to suppress the amplification of DNA from dead Gram-negative bacteria (e.g., total coliform bacteria) if they are present in pasteurized milk in large numbers. Thus, false positives may result. We developed a new method that uses real-time PCR targeting of a long DNA template (16S-23S rRNA gene, principally 2,451 bp) following EMA treatment to completely suppress the amplification of DNA of up to 7 logs (10(7) cells) of dead total coliforms. Furthermore, we found that a low dose of proteinase K (25 U/ml) removed PCR inhibitors and simultaneously increased the signal from viable coliform bacteria. In conclusion, our simple protocol specifically detects viable total coliforms in pasteurized milk at an initial count of ≥1 colony forming unit (CFU)/2.22 ml within 7.5 h of total testing time. This detection limit for viable cells complies with the requirements for the analysis of total coliforms in pasteurized milk set by the Japanese Sanitation Act (which specifies <1 CFU/2.22 ml).
    No preview · Article · May 2012 · Applied Microbiology and Biotechnology
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    ABSTRACT: Enterotoxigenic Bacteroides fragilis (ETBF) strains have been suggested to be associated with acute and persistent diarrheal disease, inflammatory bowel disease and colorectal cancer, although further epidemiological studies are needed for clarification. Here, a pilot study was performed to examine the effect of the oral administration of yogurt supplemented with a probiotic strain on the cell numbers of fecal ETBF in a healthy population. Among 420 healthy adults, 38 subjects were found to be ETBF carriers, giving a prevalence of approximately 9%. Among them, 32 subjects were enrolled in an open, randomized, parallel-group study to ingest yogurt supplemented with a probiotic strain, Bifidobacterium longum BB536 (BB536Y group), for 8 weeks, with milk provided to the control group (milk group). The cell numbers of ETBF and the dominant species of the B. fragilis group were measured by a quantitative PCR method. Compared with the baseline values, there was a significant decrease in the cell number of ETBF at week 8 in the BB536Y group but not in the milk group. Linear mixed models analysis for longitudinal data revealed a significant difference in the changes of ETBF cell number between the two groups during the intervention phase. These results imply the potential of probiotic yogurt for eliminating ETBF in the microbiota, but its clinical significance needs to be evaluated in the future. This is the first report of a possible effect of probiotic intake on ETBF in the microbiota.
    No preview · Article · Nov 2011 · Anaerobe
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    ABSTRACT: We investigated whether the oral administration of Bifidobacterium longum BB536 could ameliorate influenza virus (IFV) infection in a mice model. Mice were orally administrated BB536 or saline for 2 weeks and then infected with IFV. Orally administered BB536 significantly alleviated symptoms, reduced the loss of body weight, and inhibited viral proliferation in the lungs relative to the control group findings. Histopathological findings in the lungs were improved in the BB536 group compared to control group findings. There was no significant difference in the levels of interleukin-6 (IL-6), interferon-γ (IFN-γ), IL-10 and IL-12p40 in the lungs between the groups, but the levels of IL-6 and IFN-γ were lower (p=0.076, 0.103, respectively) in the BB536 group compared with those of control group. The levels of IL-6 and IL-10 correlated significantly with the values of weight loss, and the levels of IFN-γ correlated with the virus titers in the lungs. These results suggested the potential of the oral administration of BB536 in ameliorating IFV infection and the possible involvement of anti-inflammatory effects of BB536 in the anti-infection effects against IFV.
    Preview · Article · Aug 2011 · Biological & Pharmaceutical Bulletin
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    ABSTRACT: A total of 23 strains of bifidobacteria taxonomically belonging to five species were tested for their potent immunomodulatory effect using a combination of two methods: the NF-κB-reporter assay using a toll-like receptor 2-expressing transfectant (HEK(pTLR2) system) and the mitogenic assay using porcine Peyer's patches immunocompetent cells. Among the four preselected strains from different immunomodulatory groups, Bifidobacterium breve MCC-117 was able to efficiently modulate the inflammatory response triggered by enterotoxigenic Escherichia coli (ETEC) in a porcine intestinal epithelial (PIE) cell line. Moreover, using PIE cells and swine Peyer's patches immunocompetent cell co-culture system, we demonstrated that the immunoregulatory effect of B. breve MCC-117 was related to the capacity of the strain to influence PIE and immune cell interactions, leading to the stimulation of regulatory T cells. The results suggested that bifidobacteria that express high activity in both the HEK(pTLR2) and the mitogenic assays may behave like potential anti-inflammatory strains. The combination of the HEK(pTLR2) system, the evaluation of mitogenic activity and PIE cells will be of value for the development of new immunologically functional foods and feeds that could prevent inflammatory intestinal disorders. Although our findings should be proven in appropriate experiments in vivo, the results of the present work provide a scientific rationale for the use of B. breve MCC-117 to prevent ETEC-induced intestinal inflammation.
    Full-text · Article · Jun 2011 · FEMS Immunology & Medical Microbiology
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    ABSTRACT: A Lactococcus lactis subspecies-specific primer was designed based on their repetitive genome sequences. This primer enabled L. lactis subspecies to be identified simultaneously at both the species level and also the strain level. Based on studies using 70 strains of L. lactis and 60 strains of other non-target bacteria, the identification completely matched that obtained by the sequence of the 16S rRNA gene. However, inconsistency between phenotypic and genotypic characteristics was observed in some strains isolated from milk.
    No preview · Article · May 2011 · Systematic and Applied Microbiology
  • T Odamaki · J Z Xiao · S Yonezawa · T Yaeshima · K Iwatsuki
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    ABSTRACT: The poor survival of probiotic bacteria in commercial yogurts may limit their potential to exert health benefits in humans. The objective was to improve the survival of bifidobacteria in fermented milk. Cocultivation with some strains of Lactococcus lactis ssp. lactis improved the survival of bifidobacteria in fermented milk during refrigerated storage. Studies on one strain, Lc. lactis ssp. lactis MCC866, showed that the concentrations of dissolved oxygen were kept lower in the cocultivated fermented milk during storage compared with monocultured Bifidobacterium longum BB536 or samples cocultured with another noneffective Lc. lactis ssp. lactis strain. Degradation of genomic DNA was suppressed in the cocultivating system with Lc. lactis ssp. lactis MCC866. Several genes that participated in protection from active oxygen species (e.g., genes coding for alkyl hydroperoxide reductase and Fe(2+) transport system) were expressed at higher levels during refrigerated storage in Lc. lactis ssp. lactis MCC 866 compared with another noneffective Lc. lactis ssp. lactis strain. Concentration of free iron ion was also lower in supernatants of fermented milk cocultivated with B. longum BB536 and Lc. lactis ssp. lactis MCC866. These results suggest that Lc. lactis ssp. lactis MCC 866 is potentially superior in reducing oxygen damage and consequently improves the survival of bifidobacteria in the cocultivating system. This cocultivation system is of industrial interest for producing fermented milk containing viable bifidobacteria with long shelf life.
    No preview · Article · Mar 2011 · Journal of Dairy Science
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    ABSTRACT: The gram-positive bacterial genus Lactococcus has been taxonomically classified into seven species (Lactococcus lactis, Lactococcus garvieae, Lactococcus piscium, Lactococcus plantarum, Lactococcus raffinolactis, Lactococcus chungangensis and Lactococcus fujiensis). This study aimed to develop a novel multiplex polymerase chain reaction (PCR) primer set for the identification of the seven lactococcal species, as well as to differentiate the two industrially important dairy subspecies, L. lactis subsp. lactis and L. lactis subsp. cremoris. A multiplex PCR primer set was designed based on the nucleotide sequences of the 16S rRNA gene of the seven lactococcal species. The specificity of the established one-step multiplex PCR scheme was verified using more than 200 bacterial strains, in which a complete sequence match was confirmed by partial sequencing of their 16S rRNA gene. The one-step multiplex PCR enables the identification and speciation of bacterial strains belonging to the genus Lactococcus and the differentiation of strains of L. lactis subsp. lactis and L. lactis subsp. cremoris. This work provides an efficient method for identification of lactococcal strains of industrial importance.
    No preview · Article · Feb 2011 · Letters in Applied Microbiology
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    ABSTRACT: The aim of the present study was to evaluate the anti-obesity activity of a probiotic bifidobacterial strain in a mouse model with obesity induced by a high-fat diet. The mice were fed a high-fat diet supplemented with Bifidobacterium breve B-3 at 10(8) or 10(9) CFU/d for 8 weeks. B. breve B-3 supplementation dose-dependently suppressed the accumulation of body weight and epididymal fat, and improved the serum levels of total cholesterol, fasting glucose and insulin. The bifidobacterial counts in the caecal contents and feces were significantly increased with the B. breve B-3 administration. The expression of genes related to fat metabolism and insulin sensitivity in the gut and epididymal fat tissue was up-regulated by this administration. These results suggest that the use of B. breve B-3 would be effective in reducing the risk of obesity.
    No preview · Article · Aug 2010 · Bioscience Biotechnology and Biochemistry
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    ABSTRACT: Twenty-seven elderly subjects (mean age 86.7+/-6.6 years) were pre-administered a test food containing 1x10(11) cfu of BB536 daily for 5 weeks (P1), during which they also received influenza vaccination at week 3. The subjects were then randomized to a BB536 group and a placebo group for 14 weeks (P2). The proportion of subjects who contracted influenza was significantly lower in BB536 group than in the to placebo group. The proportion of subjects with fever was also significantly lower in the BB536 group than in the placebo group. In the P1 period, the NK cell activity and the bactericidal activity of the neutrophils were significantly higher at week 5 than to before BB536 administration. In the P2 period, although NK cell activity and neutrophilic activities declined at the end of the study in both the placebo and the BB536 group, neutrophil phagocytic activity and NK cell activity tended to maintain slightly higher levels in the BB536 group than in the placebo group. These results suggest that continuous ingestion of BB536 reduces the incidence of influenza and fever, probably by potentiating innate immunity.
    No preview · Article · May 2010 · Bioscience Biotechnology and Biochemistry
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    ABSTRACT: Cultivation of bifidobacteria in milk is a difficult and industrially valuable task. In this paper, we report the finding of a novel technique to improve the growth of bifidobacteria in dairy products and the results of mechanism studies. The growth of bifidobacteria in skim milk medium was found to be stimulated upon cocultivation with certain strains of Lactococcus lactis ssp. lactis. Bifidobacterium growth-stimulating (BGS) activity was observed on a wide range of bifidobacterial species. Bifidobacterium growth-stimulating activity was associated with the ability to grow in skim milk medium and the presence of a cell wall-anchored proteinase (PrtP) in Lc. lactis ssp. lactis. Studies on one strain, Lc. lactis ssp. lactis MCC857, showed that crude PrtP extracts and casein hydrolysates exhibited BGS activity. The casein hydrolysate BGS activity was found in the low molecular weight fraction by HPLC separation. A combination of 2 AA, Met and Leu, was found to account for a large portion of the casein hydrolysate BGS activity. In conclusion, this cocultivation system is highly efficient and industrially applicable for the production of fermented milk with high cell counts of bifidobacteria.
    No preview · Article · May 2010 · Journal of Dairy Science
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    J Minami · K Yoshida · T Soejima · T Yaeshima · K Iwatsuki
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    ABSTRACT: Ethidium bromide monoazide (EMA) has been determined to cause delay in DNA amplification from dead bacteria at real-time PCR. However, there is concern that the increasing EMA concentration to suppress amplification from high number of dead bacteria also affects live bacteria. The aim is to disclose a novel application of EMA for food hygienic test. We performed a low-dose double EMA treatment. Live or heat-dead Enterobacter sakazakii (reclassified as Cronobacter spp.) in 10% powdered infant formula (PIF) solution was subjected to a treatment with 20 μg ml(-1) of EMA followed by a treatment with 10 μg ml(-1) of EMA without washing, and direct real-time PCR. We observed that DNA amplification from 10(7) cells ml(-1) of dead Ent. sakazakii was completely suppressed within 50 cycles of PCR, whereas 10(2) -10(3) cells ml(-1) of viable cells could be detected. When a 3-h enrichment step in liquid medium was included after the first EMA treatment, live Ent. sakazakii could be detected at initial levels of 10(0) -10(2) cells ml(-1) . We compared the low-dose double-treated EMA-PCR with the culture method using 80 samples of PIF, and completely correlative results were obtained for both methods. We concluded that the newly developed low-dose double-treated EMA-PCR is a very effective tool for live Ent. sakazakii detection in PIF. We focused on the specific nature of photoreactive compound that residual EMA is cancelled by irradiation. We were successful in treating bacteria with EMA in gradient concentration to increase live and dead distinction ability.
    Preview · Article · Mar 2010 · Journal of Applied Microbiology
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    ABSTRACT: The aim of the present study was to analyze the antibiotic susceptibility of bifidobacterial strains distributed in the Japanese market. A total of 23 strains, including probiotic isolates from foods, supplements, pharmaceuticals and reference strains of each species (or subspecies), were tested for susceptibility to 15 antibiotics by the broth microdilution method and examined for the presence of possible resistant determinants. The strains were susceptible overall to chloramphenicol, ampicillin, vancomycin and linezolid, and were intrinsically resistant to aminoglycoside group agents. Susceptibility to erythromycin, clindamycin, rifampicin, tetracycline and trimethoprim varied among the strains. All strains of Bifidobacterium animalis subsp. lactis were resistant to tetracycline and appeared to harbor tet(W) genes. No risk factor for safety was found for bifidobacterial strains distributed in the Japanese market in respect of their antimicrobial resistance, although the presence of the tet(W) gene in some strains stresses the need for future evaluation.
    No preview · Article · Feb 2010 · Bioscience Biotechnology and Biochemistry
  • Masamichi Muto · Fumiaki Abe · Tomoko Yaeshima · Keiji Iwatsuki

    No preview · Article · Jan 2010
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    ABSTRACT: We previously demonstrated orally administered bovine lactoperoxidase (LPO) ameliorated dextran sulfate sodium-induced colitis in mice. Here, we examine the mechanism of action of LPO. Three days after colitis induction, expression of interferon-γ mRNA in colonic tissue was significantly decreased in mice administered LPO; while mRNA expression of interleukin (IL)-10 and regulatory T cell (Treg) marker, Foxp3, were significantly increased. The proportion of CD4+CD25+ Tregs in peripheral CD4+ T cells was also significantly elevated when LPO was administered. Nine days after colitis induction, the severity of colitis symptoms, including body weight loss and colon shortening, was reduced and expression of IL-10 mRNA was increased in mice administered LPO. The proportion of CD4+CD25+ Tregs in peripheral leukocytes was also significantly elevated when LPO was administered. These results suggest LPO ameliorates colitis by up-regulating colonic anti-inflammatory cytokines and maintaining peripheral regulatory T cells.
    No preview · Article · Nov 2009 · International immunopharmacology
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    ABSTRACT: This study investigated the potential utilization of lacto-N-biose I (LNB) by individual strains of bifidobacteria. LNB is a building block for the human milk oligosaccharides, which have been suggested to be a factor for selective growth of bifidobacteria. A total of 208 strains comprising 10 species and 4 subspecies were analyzed for the presence of the galacto-N-biose/lacto-N-biose I phosphorylase (GLNBP) gene (lnpA) and examined for growth when LNB was used as the sole carbohydrate source. While all strains of Bifidobacterium longum subsp. longum, B. longum subsp. infantis, B. breve, and B. bifidum were able to grow on LNB, none of the strains of B. adolescentis, B. catenulatum, B. dentium, B. angulatum, B. animalis subsp. lactis, and B. thermophilum showed any growth. In addition, some strains of B. pseudocatenulatum, B. animalis subsp. animalis, and B. pseudolongum exhibited the ability to utilize LNB. With the exception for B. pseudocatenulatum, the presence of lnpA coincided with LNB utilization in almost all strains. These results indicate that bifidobacterial species, which are the predominant species found in infant intestines, are potential utilizers of LNB. These findings support the hypothesis that GLNBP plays a key role in the colonization of bifidobacteria in the infant intestine.
    Preview · Article · Oct 2009 · Applied and Environmental Microbiology
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    F Abe · S Tomita · T Yaeshima · K Iwatsuki
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    ABSTRACT: Human bifidobacteria are more sensitive to external environmental factors than animal bifidobacteria, and it is difficult to ensure their stable survival in yogurt. The purpose of this investigation was to observe the survival of human bifidobacteria in yogurts produced under various production conditions. Frozen or lyophilized bifidobacteria starters containing Bifidobacterium longum BB536 originally isolated from an infant, and commercial lyophilized yogurt starters were used for yogurt preparation. After producing yogurts under various conditions, the survival of bifidobacteria in these yogurts over various storage periods was observed. Although there were some differences in bifidobacterial survival in yogurt between various production conditions, more than 1.0 x 10(7) CFU g(-1) of Bif. longum survived in yogurt after 35 days' storage at 5 degrees C. Lower fermentation temperature (37 degrees C) and inclusion of Lactococcus lactis in the starter significantly (P < 0.05) improved survival of Bif. longum in the yogurt. In this investigation, the human bifidobacterial strain Bif. longum survived adequately in yogurt, although the fermentation temperature and starter composition affect bifidobacterial survival. This investigation indicates that stable probiotic yogurt using human bifidobacteria can be produced by choosing optimal production conditions.
    Preview · Article · Aug 2009 · Letters in Applied Microbiology
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    ABSTRACT: 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.
    No preview · Article · Aug 2009 · Anaerobe

Publication Stats

1k Citations
88.43 Total Impact Points


  • 1991-2013
    • Morinaga Milk Industry Co., Ltd.
      Edo, Tōkyō, Japan
  • 2009
    • National Agriculture and Food Research Organization
      Tsukuba, Ibaraki, Japan
    • Toyo College of Food Technology
      Kawanishi, Hyōgo, Japan