I was bashful by nature. In elementary school, I was enthusiastic about painting pictures, posters, and calligraphy, and making butterfly specimens and models. When I entered the middle school of Seikei Gakuen, I was fortunate to have good teachers and friends. Prof. Kusatao Nakamura taught us the “Preciousness of the pureness of heart”, which is the principle of my life. After World War II, school classes reopened. I was deeply moved by the lecture of botany by Prof. Fumio Maekawa, and had a notion that I should like to make research my lifework. I went to high school and had the worries of my life. During that time, it was the book Gakusei ni atau by Prof. Eijirou Kawai, and a speech by Prof. Tadao Yanaihara, that sustained my heart. In 1953, I entered the postgraduate course of the University of Tokyo, and received the guidance of Prof. Yuichi Ochi. This matter was decisive for my life. First of all, I developed a new medium, BL agar, for culturing intestinal bacteria, and then I discovered that Bifidus bacteria was one of the predominant organisms in human adults. This discovery became the basis of my research until today. For two years from 1964, I studied abroad in Germany and made good friends, to whom I owe an inestimable debt of gratitude. After returning to Japan, I discovered a number of rules governing the intestinal ecosystem. Thus, a new interdisciplinary field, intestinal bacteriology, was established. Subsequently, I discovered the health effects of fermented milks and oligosaccharides and proposed “biogenics”. I firmly believe that the fruit of creation is granted as a result of endeavoring with a pure heart.

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Weaning piglets are continuously exposed to various viruses. The antiviral effects of lactic acid bacteria (LAB) have been confirmed mainly in humans and mice, while few studies have been conducted in livestock. In this study, we evaluated the effect of oral administration of Enterococcus faecalis strain EC-12 (EC-12) on the gene expressions of antiviral cytokines in weaning piglets. Piglets were allocated to the EC-12-administered group (E group) and the no-treatment control group (C group). The small intestinal tissue, the mesenteric lymph node (MLN) cells and the splenocytes were collected from the piglets. The tissue and cells were co-cultured with a live vaccine of porcine reproductive respiratory syndrome virus, porcine epidemic diarrhea virus or EC-12. After the incubation, the gene expressions of IFN-γ and TNF-α in the tissue and cells were evaluated. The gene expressions of IFN-γ in the MLN cells and TNF-α in the splenocytes were significantly higher in the E group than in the C group. However, the increase in the gene expression of antiviral cytokines was observed independently of the antigen treatments. The results of the present study suggest that oral administration of EC-12 did not increase the response of immune cells to specific viral antigens but increased the baseline gene expression of antiviral cytokines.

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The intestinal microbiota compositions of 92 men living in Japan were identified following consumption of identical meals for 3 days. Fecal samples were analyzed by terminal restriction fragment length polymorphism with 4 primer-restriction enzyme systems, and the 120 obtained operational taxonomic units (OTUs) were analyzed by Data mining software focusing on the following 5 characteristics, namely, age, body mass index, present smoking habit, cessation period of previous smokers and drinking habit, according to the answers of the subjects. After performing Data mining analyses with each characteristic, the details of the constructed Decision trees precisely identified the subjects or discriminated them into various suitable groups. Through the pathways to reach the groups, practical roles of the related OTUs and their quantities were clearly recognized. Compared with the other identification methods for OTUs such as bicluster analyses, correlation coefficients and principal component analyses, the clear difference of this Data mining technique was that it set aside most OTUs and emphasized only some closely related ones. For example for a selected characteristic, such as smoking habit, only 7 OTUs out of 120 were able to identify all smokers, and the remaining 113 OTUs were thought of as data noise for smoking. Data mining analyses were affirmed as an effective method of subject discrimination for various physiological constitutions. The species of bacteria that were closely related to heavy smokers, i.e., HaeIII-291, were also discussed.

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The intestinal microbiota compositions of 92 Japanese men were identified following consumption of identical meals for 3 days, and collected feces were analyzed through terminal restriction fragment length polymorphism. The obtained operational taxonomic units (OTUs) and subjects’ smoking and drinking habits, which had 2 nominal partitions, yes or no, were analyzed by Data mining software. Identification of subjects for each habit was successfully performed and reported previously, but the identification accuracy was closely dependent on the species of the applied restriction enzymes for PCR. For the sake of better selection of enzymes and understanding the mechanisms of Data mining analysis, 516f-BslI and 516f-HaeIII, 27f-MspI and 27f-AluI and 35f-HhaI, 35f-MspI and 35f-AluI, altogether 7 enzymes, were examined comparatively. Data mining analysis provides a Decision tree for identification of subjects and their dividing pathways that is produced using a limited number of OTUs, which affects the accuracy of the results. The present report discusses not only a global comparison of accuracies for characteristics, but also the detailed mechanisms that result in better or worse results and the practical roles and functions of OTUs. The OTU at the 1st step of the constructed Decision tree was the most important for any identification, and for all cases, the combination of subsequent OTUs, which formed later in the Decision tree, was also unignorable. Detailed dividing pathways were traced and compared for the 7 enzymes and the future supporting ideas were provided for better Data mining analysis of the human intestinal microbiota.

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This study aimed to examine the mechanism for differential effects of low- (LPPS) and high-phosphorus (HPPS) potato starches and high-amylose cornstarch (HACS) on rat cecal fermentation, the n-butyrate proportion in particular. In ileorectostomized rats, the in vivo resistant starch (RS) contents were determined to be 66% (LPPS), 66% (HPPS) and 36% (HACS), but the carbohydrate/nitrogen (C/N) ratios of the ileal digesta were comparable among the respective starch diets. In intact rats fed diets including similar amounts of RS, the cecal n-butyrate proportions in the LPPS- and HPPS-fed rats were equally higher than in the HACS-fed rats. The cecal starch contents were fivefold greater in the LPPS- and HPPS-fed rats than in the HACS-fed rats. The results suggest that potato starches and HACS are not equivalent n-butyrate producers in the rat cecum and that the slower fermentation rate of potato starches relative to HACS might be responsible for the higher n-butyrate proportion.

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Lactobacillus delbrueckii strains were assessed for their degradation patterns of various carbohydrates with specific reference to inulin-type fructans in comparison with those of Lactobacillus paracasei strains. Firstly, growth curves on glucose, fructose, sucrose and inulin-type fructans with increasing degrees of fructose polymerization (i.e., 1-kestose, fructo-oligosaccharides and inulin) of the strains were compared. L. paracasei DSM 20020 grew well on all these sugars, while the growth rates of the 4 L. delbrueckii strains were markedly higher on the fructans with a greater degree of polymerization than on fructose and sucrose. Secondly, sugar compositions of spent cultures of the strains of L. delbrueckii and L. paracasei grown in mMRS containing either the fructans or inulin were determined by thin layer chromatography, in which the spent cultures of L. paracasei DSM 20020 showed spots of short fructose and sucrose fractions, whereas those of the L. delbrueckii strains did not show such spots at all. These results suggest that, unlike the L. paracasei strains, the L. delbrueckii strains do not degrade the inulin-type fructans extracellularly, but transport the fructans capable of greater polymerization preferentially into their cells to be degraded intracellularly for their growth.

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The yacon (Smallanthus sonchifolius) tuber was examined with regard to its prebiotic effects compared with commercialized fructo-oligosaccharides (FOS). A feed containing 10% yacon tuber, which is equivalent to 5% commercialized FOS in terms of the amount of fructo-oligosaccharides (GF2, GF3 and GF4), was administrated to rats for 28 days. The yacon diet changed the intestinal microbial communities beginning in the first week, resulting in a twofold greater concentration of cecal short-chain fatty acids (SCFAs). The SCFA composition differed, but the cecal pH in rats fed yacon tuber was equal to that in rats fed FOS. Serum triglycerides were lower in rats fed yacon compared with rats fed FOS and the control diet. Cecal size was greater with the yacon tuber diet compared with the control diet. The abundant fermentation in the intestines created a selective environment for the intestinal microbiota, which included Lactobacillus acidophilus, Bifidobacterium pseudolongum, Bifidobacterium animalis and Barnesiella spp. according to identification with culture-independent analysis, 16S rRNA gene PCR-DGGE combined with cloning and sequencing. Barnesiella spp. and B. pseudolongum were only found in the rats fed the yacon diet, while L. acidophilus and B. animalis were found in abundance in rats fed both the yacon and FOS diets. The genus Barnesiella has not previously been reported to be associated with yacon or FOS fermentation. We concluded that the physiological and microbiological effects of the yacon tuber were different from those of FOS. Differences in cecal size, blood triglycerides and microbial community profiles including their metabolites (SCFAs) between the yacon tuber and FOS were shown to be more greatly affected by the yacon tuber rather than FOS.

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