Kimiko Minamida

Asaccharobacter celatus gen. nov., sp. nov., isolated from rat caecum

An obligately anaerobic and equol-producing bacterium, designated strain do03T, was isolated from the caecal content of a rat. Cells were Gram-positive, non-spore-forming rods. The results from a phylogenetic analysis based on 16S rRNA gene sequences showed that strain do03T formed a separate line of descent in the phylogenetic cluster of the family Coriobacteriaceae. The strain was unable to metabolize glucose or other carbohydrates as sole carbon sources; growth was enhanced in the presence of arginine. The cell wall contained meso-diaminopimelic acid. The major fatty acid was C18 : 1cis9 (54.0 %). The strain had one unidentified predominant (91.9 %) quinone that was not menaquinone, methylmenaquinone, demethylmenaquinone, ubiquinone or rhodoquinone. The DNA G+C content was 63 mol%. The data presented in this work show that strain do03T differs from members of the related recognized genera Eggerthella and Denitrobacterium at both the phylogenetic and phenotypic level. Therefore, the strain constitutes a novel genus and species, for which the name Asaccharobacter celatus gen. nov., sp. nov. is proposed. The type strain of the type species is do03T (=JCM 14811T=DSM 18785T=AHU 1763T).

Conversion of cholic acid and chenodeoxycholic acid into their 7-oxo derivatives by Bacteroides intestinalis AM-1 isolated from human feces.

Secondary bile acid-producing bacteria were isolated from human feces to improve our appreciation of the functional diversity and redundancy of the intestinal microbiota. In total, 619 bacterial colonies were isolated using a nutrient-poor agar medium and the level of secondary bile acid formation was examined in each by a liquid culture, followed by thin-layer chromatography. Of five strains analyzed by 16S rRNA gene sequencing and biochemical testing, one was identified as Bacteroides intestinalis AM-1, which was not previously recognized as a secondary bile-acid producer. GC-MS revealed that B. intestinalis AM-1 converts cholic acid (CA) and chenodeoxycholic acid into their 7-oxo derivatives, 7-oxo-deoxycholic acid (7-oxo-DCA) and 7-oxo-lithocholic acid, respectively. Thus, B. intestinalis AM-1 possesses 7alpha-hydroxysteroid dehydrogenase (7alpha-HSDH) activity. In liquid culture, B. intestinalis AM-1 showed a relatively higher productivity of 7-oxo-DCA than Escherichia coli HB101 and Bacteroides fragilis JCM11019(T), which are known to possess 7alpha-HSDH activity. The level of 7alpha-HSDH activity was higher in B. intestinalis AM-1 than in the other two strains under the conditions tested. The 7alpha-HSDH activity in each of the three strains is not induced by CA; instead, it is regulated in a growth phase-dependent manner.

Pediococcus pentosaceus NB-17 for Probiotic Use

The plant-derived Pediococcus pentosaceus NB-17 was isolated from Japanese traditional vegetable pickles. The production of cytokines from mouse spleen cells co-cultivated with heat-killed bacteria was investigated in vitro. The bacteria significantly induced secretion levels of interferon (IFN)-gamma and interleukin (IL)-12 p70, and suppressed IL-4 productions in ovalbumin (OVA) sensitized mouse spleen cells. Therefore, the bacteria could effectively stimulate immune activities and showed allergic inhibitory effects. Further study on acid tolerance was performed under simulated gastric conditions and NB-17 showed resistance to simulated gastric acidity at pH 3.0 and pH 2.5. Moreover, after oral administration of the intact cells to rats, bacterial colonies derived from feces were analyzed by random amplification polymorphic DNA (RAPD). It was confirmed that the administered strain NB-17 remained alive in feces. These results suggest the possibility to use the P. pentosaceus NB-17 as functional foods.

Effects of Ingestion of Difructose Anhydride III (DFA III) and the DFA III-Assimilating Bacterium Ruminococcus productus on Rat Intestine

We have isolated a difructose anhydride III (DFA III)-assimilating bacterium, Ruminococcus productus AHU1760, from human. After an acclimation period of 1 week, male Sprague-Dawley rats (5 weeks old) were divided into four groups (control diet, R. productus diet, DFA III diet, and R. productus + DFA III diet; n=8) and fed the assigned test diets for 2 weeks. The viable count of administered R. productus was 4.9×107 CFU/d in R. productus-fed rats and 4.7×107 CFU/d in R. productus + DFA III-fed rats. Survival in cecal content of this strain was confirmed by randomly amplified polymorphic DNA. The ratio of secondary bile acids in feces in R. productus + DFA III-fed rats decreased the same as that in rats fed only DFA III. The viable count of lactobacilli and bifidobacteria, known as beneficial bacteria, increased more in R. productus + DFA III-fed rats than in control or R. productus-fed rats. A combination of R. productus and DFA III might improve the balance of intestinal microbiota to a healthier condition.

Effects of dietary fiber with Bacillus coagulans lilac-01 on bowel movement and fecal properties of healthy volunteers with a tendency for constipation

To elucidate the effects of Lilac LAB (Bacillus coagulans lilac-01 and okara [soy pulp] powder) on bowel movements/fecal properties, we conducted a double-blind placebo-controlled randomized trial with healthy Japanese volunteers with a tendency for constipation (n = 297). The subjects ingested 2 g/d placebo (okara powder) or test food (Lilac LAB, 1 × 108 CFU) once a day for 2 weeks. In the test group of functionally constipated subjects, the changes in the average scores of self-reported fecal size, sensation of incomplete evacuation, and defecation frequency were significantly improved compared to the placebo group (p < 0.05), and fecal color and odor tended to improve (p = 0.07). In the test food group of all subjects and among the non-functionally constipated subjects, the fecal size tended to improve compared to the placebo group (p = 0.06, p = 0.07, respectively). Lilac LAB was effective in improving bowel movements and fecal properties in functionally constipated persons. Graphical Abstract Test food (Lilac LAB) was effective in improving bowel movements and fecal properties compared to placebo (okara powder) in functionally constipated persons.

Combination of soya pulp and Bacillus coagulans lilac-01 improves intestinal bile acid metabolism without impairing the effects of prebiotics in rats fed a cholic acid-supplemented diet.

Intestinal bacteria are involved in bile acid (BA) deconjugation and/or dehydroxylation and are responsible for the production of secondary BA. However, an increase in the production of secondary BA modulates the intestinal microbiota due to the bactericidal effects and promotes cancer risk in the liver and colon. The ingestion of Bacillus coagulans improves constipation via the activation of bowel movement to promote defaecation in humans, which may alter BA metabolism in the intestinal contents. BA secretion is promoted with high-fat diet consumption, and the ratio of cholic acid (CA):chenodeoxycholic acid in primary BA increases with ageing. The dietary supplementation of CA mimics the BA environment in diet-induced obesity and ageing. We investigated whether B. coagulans lilac-01 and soya pulp influence both BA metabolism and the maintenance of host health in CA-supplemented diet-fed rats. In CA-fed rats, soya pulp significantly increased the production of secondary BA such as deoxycholic acid and ω-muricholic acids, and soya pulp ingestion alleviated problems related to plasma adiponectin and gut permeability in rats fed the CA diet. The combination of B. coagulans and soya pulp successfully suppressed the increased production of secondary BA in CA-fed rats compared with soya pulp itself, without impairing the beneficial effects of soya pulp ingestion. In conclusion, it is possible that a combination of prebiotics and probiotics can be used to avoid an unnecessary increase in the production of secondary BA in the large intestine without impairing the beneficial functions of prebiotics.