Hiroshi Kitagaki

Investigation of the influence of alive or dead dietary lactic acid bacteria, specifically Lactobacillus gasseri, on mice fed a tyrosine-rich diet was conducted in this study. Mice fed a tyrosine-rich diet exhibited increased p-cresol levels in the serum and cecum and deteriorated skin characteristics in terms of skin moisture and transepidermal water loss. These conditions were partially ameliorated by the intake of lactic acid bacteria. To gain insight into the mechanism, the intestinal microbiota of mice fed lactic acid bacteria was examined. The results revealed an increase in bacteria including genus Faecalibacterium and Lactobacillus in fecal samples from mice fed lactic acid bacteria. Muribaculaceae was most associated with the added group of alive or dead L. gasseri. These findings indicate that lactic acid bacteria inhibit the conversion of tyrosine to p-cresol in the colon, thereby ameliorating skin disorders.

Objectives: Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic disorder of the liver and affects many people worldwide. Intestinal bacteria are thought to be involved in the pathological progression of NAFLD; therefore, improving the intestinal microbiota may be important in controlling NAFLD. In this study, we assessed the effects of water-soluble cellulose acetate (WSCA) on the intestinal microbiota in a non-alcoholic steatohepatitis (NASH) mouse model. Methods: NASH model (STAM mice) was created by streptozotocin injection and feeding the mice a high-fat diet. The serum biochemical parameters were analyzed. Intestinal bacterial populations were analyzed using paired-end sequencing of 16S rRNA, 18S rRNA, and internal transcribed spacer gene. Results: Our findings indicated that WSCA administration tends to improve the serum alanine aminotransferase and glucose levels in STAM mice and decreased the alpha diversity and altered the beta diversity of their intestinal microbiota. Additionally, WSCA intake resulted in an increase in the abundance of Coriobacteriaceae_UCG-002 and a decrease in the abundance of Enterobacter. Conclusions: WSCA intake can alter specific microbial compositions to improve blood glucose levels and liver functions and may improve the pathogenesis of NAFLD.

Skin barrier function, prevent colon cancer, head and neck cancer, and decrease liver cholesterol. However, the mechanism of action has not yet been elucidated. In this study, we propose a new working hypothesis regarding the health benefits and functions of glucosylceramide: decreased fecal hardness. This hypothesis was verified using an in vitro hardness test. The hardness of feces supplemented with glucosylceramide was significantly lower than that of the control. Based on these results, a new working hypothesis of dietary glucosylceramide was conceived: glucosylceramide passes through the small intestine, interacts with intestinal bacteria, increases the tolerance of these bacteria toward secondary bile acids, and decreases the hardness of feces, and these factors synergistically result in in vivo effects. This hypothesis forms the basis for further studies on the health benefits and functions of dietary glucosylceramides.

Cosmetics in the world have various characteristics, but differences in their effects on skin-domesticated bacteria were not known. In this study, to obtain insights into their effect on skin microbiota, we established an anaerobic culture and short-chain fatty acid measurement system using Staphylococcus epidermidis, a representative bacterium of indigenous skin bacteria. This system was used to extract the characteristics of nine cosmetics and classify them. Cosmetics containing ferments of rice and soy were clustered in the vicinity, although one cosmetic containing soy ferment was clustered distantly from other similar cosmetics. Cosmetics from South Asia and those containing natural plant extracts were clustered in the vicinity. This trial could be utilized as a pattern map of cosmetics in terms of their effects on skin microbiota.

Cosmetics have various characters, but there have been no studies which classified the properties of cosmetics based on their effects on skin-domesticated bacteria. In this study, we established an anaerobic culture and short-chain fatty acid measurement system using Staphylococcus epidermidis, a representative bacterium of indigenous skin bacteria. Furthermore, this system was used to extract and classify the characteristics of 9 cosmetics. Cosmetics containing ferments of rice and soy were clustered in the vicinity, although one cosmetic containing soy ferment was clustered distant from other similar cosmetics. Cosmetics from South Asia and those containing natural plant extracts were clustered in the vicinity. These results show that this method can be utilized as a cosmetics pattern map, and will provide a method to prevent growth of opportunistic bacteria.

The skin covers our entire body and is said to be the “largest organ of the human body”. It has many health-maintaining functions, such as protecting the body from ultraviolet rays and dryness and maintaining body temperature through energy metabolism. However, the number of patients suffering from skin diseases, including atopic dermatitis, is increasing due to strong irritation of the skin caused by detergents that are spread by the development of the chemical industry. The skin is inhabited by about 10²–10⁷ cells/cm² and 1000 species of commensal bacteria, fungi, viruses, and other microorganisms. In particular, metabolites such as fatty acids and glycerol released by indigenous skin bacteria have been reported to have functional properties for the health of the skin. Therefore, skin-domesticating bacteria and the metabolites derived from those bacteria are used in many skincare product ingredients and function as probiotic cosmetics. Japanese traditional fermented stuff, used as foods in Japan for over 1300 years, are now being applied as fermented cosmetics. Fermented cosmetics are expected to have multifaceted health functionality and continue to grow as products in the natural skincare product market. In this review, we consider approaches to skin health using fermented cosmetics and modulation of skin microflora metabolites.

Glucosylceramide is present in many foods, such as crops and fermented foods. Most glucosylceramides are not degraded or absorbed in the small intestine and pass through the large intestine. Glucosylceramide exerts versatile effects on colon tumorigenesis, skin moisture, cholesterol metabolism and improvement of intestinal microbes in vivo. However, the mechanism of action has not yet been fully elucidated. To gain insight into the effect of glucosylceramide on intestinal microbes, glucosylceramide was anaerobically incubated with the dominant intestinal microbe, Blautia coccoides, and model intestinal microbes. The metabolites of the cultured broth supplemented with glucosylceramide were significantly different from those of broth not treated with glucosylceramide. The number of Gram-positive bacteria was significantly increased upon the addition of glucosylceramide compared to that in the control. Glucosylceramide endows intestinal microbes with tolerance to secondary bile acid. These results first demonstrated that glucosylceramide plays a role in the modification of intestinal microbes.

The first development method of brewery shochu yeast focusing on chromosomal aneuploidy is reported in this study. Euploidy diploid shochu yeast S-3 was treated with a microtubule inhibitor, nocodazole, for the purpose of inducing aneuploidy. Next, 2,3,5-triphenyl tetrazolium chloride (TTC) staining and the growth rate were investigated to select aneuploids. Aneuploids were selected at a frequency of 8.2 × 10⁻⁴, which was significantly higher than that of the control group, mainly at chromosomes I, II, III, IX, XII, XIII, and XVI. The acquired aneuploids were evaluated for their metabolic and brewing characteristics. A hierarchical cluster analysis based on endogenous metabolite data discriminated euploid S-3 and aneuploids. In addition, principal-component analysis of the constituents of the broth brewed with the strains discriminated between euploid S-3 and aneuploids. Sensory evaluation of the broth brewed with euploid S-3 and aneuploids showed that it tended to differ in aroma and taste. Specific ethanol production rates of the aneuploids were not deteriorated. The method of this selection made it possible to efficiently obtain aneuploids with various brewing characteristics from brewer’s yeast, which do not correspond to genetically modified organisms. This novel breeding method focusing on chromosomal aneuploidy will facilitate the development of novel shochu yeast strains.

The worldwide increase in nonalcoholic fatty liver disease (NAFLD) is a major public health problem. Obesity and diabetes are risk factors for NAFLD and the development of liver fibrosis is a risk factor for liver cancer. Periodontal disease bacteria can also exacerbate NAFLD. We previously reported that amazake, a traditional Japanese fermented food, improves the quality of life (QOL) of patients with liver cirrhosis. In this study, we investigated the effect of amazake intake on NAFLD patients with periodontal disease. Ten patients (mean age: 57.1 ± 19.2 years) consumed 100 g of amazake daily for 60 days. On days 0 and 60, their body mass index (BMI), body fat percentage, serum biochemical parameters, periodontal disease bacteria in saliva, and ten visual analog scales (VASs), namely, sense of abdomen distension, edema, fatigue, muscle cramps, loss of appetite, taste disorder, constipation, diarrhea, depression, and sleep disorder, were measured. For periodontal bacteria, the numbers of six types of bacteria in saliva (Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Fusobacterium necleatum) and P. gingivalis-specific fimA genotype were determined. After 60 days of amazake consumption, eosinophils (p < 0.05), immune reactive insulin (IRI) (p < 0.01), and HOMA-IR (p < 0.05) had significantly increased and tumor necrosis factor α (TNFα) (p < 0.01), muscle cramps (p < 0.05), and depression (p < 0.05) had significantly decreased. All subjective symptoms improved after amazake intake. No change was observed in the periodontal bacteria. In conclusion, amazake significantly decreased TNFα and improved the QOL of the patients with NAFLD and periodontitis. However, caution should be exercised because amazake, which is manufactured using techniques that lead to concentrations of glucose from the saccharification of rice starch, may worsen glucose metabolism in NAFLD patients. Amazake may be an effective food for improving the symptoms of a fatty liver if energy intake is regulated.