Publications by authors named "Hiroshi Kitagaki"

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.

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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.

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Although most fungi cause pathogenicity toward human beings, dynasties of the East Asian region have domesticated and utilized specific fungi for medical applications. The Japanese dynasty and nation have domesticated and utilized fermented with non-pathogenic fungus for more than 1300 years. Recent research has elucidated that contains medicinal substances such as Taka-diastase, acid protease, glycosylceramide, acid, oligosaccharides, ethyl-α-d-glucoside, ferulic acid, ergothioneine, pyroglutamyl leucine, pyranonigrin A, resistant proteins, deferriferrichrysin, polyamines, -stimulating peptides, angiotensin I-converting enzyme inhibitor peptides, 14-dehydroergosterol, beta-glucan, biotin, and citric acid.

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The mechanism of pyruvate-underproduction of aneuploid sake yeast was investigated in this study. In our previous report, we revealed that an increase in chromosome XI decreases pyruvate productivity of sake yeast. In this report, we found that increased copy number of CCP1, which is located on chromosome XI and encodes cytochrome-c peroxidase, decreased the pyruvate productivity of sake yeasts.

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Addition of amino acids to fermentation media affects the growth and brewing profiles of yeast. In addition, retaining mitochondrial activity during fermentation is critical for the fermentation profiles of brewer's yeasts. However, a concrete mechanism linking amino acids in fermentation media with mitochondrial activity during fermentation of brewer's yeasts is yet unknown.

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Together with the worldwide Washoku (traditional Japanese foods and drinks) boom, interest in sake, a traditional Japanese alcoholic drink, is increasing around the world. There are few scientific analyses and studies on the production of sake or the final product itself. We show the diversity of bacterial contaminants during sake production and investigated the effects of different ingredients on sake (for example, amino acids).

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, which is manufactured by proliferating non-pathogenic fungus on steamed rice, is the base for Japanese traditional fermented foods. We have revealed that and related Japanese fermented foods and drinks such as amazake, shio-, unfiltered sake and miso contain abundant glycosylceramide. Here, we report that feeding of glycosylceramide to obese mice alters the cholesterol metabolism .

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At present, the quantitation of the mycelial weight of the industrially important non-pathogenic fungus Aspergillus oryzae, which is used for manufacturing koji, is performed by quantitating N-acetylglucosamine. However, since N-acetylglucosamine is a cell wall component, the extraction procedure is costly and tedious, and its quantitative performance is poor. Here, we report a novel method for the quantitation of A.

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In the manufacture of sake, Japanese traditional rice wine, sake yeast is fermented with koji, which is steamed rice fermented with the non-pathogenic fungus . During fermentation, sake yeast requires lipids, such as unsaturated fatty acids and sterols, in addition to substances provided by koji enzymes for fermentation. However, the role of sphingolipids on the brewing characteristics of sake yeast has not been studied.

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The effect of chromosomal aneuploidy on the brewing characteristics of brewery yeasts has not been studied. Here we report that chromosomal aneuploidy in sake brewery yeast () leads to the development of favorable brewing characteristics. We found that pyruvate-underproducing sake yeast, which produces less off-flavor diacetyl, is aneuploid and trisomic for chromosomes XI and XIV.

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Background: The Japanese traditional cuisine, Washoku, considered to be responsible for increased longevity among the Japanese, comprises various foods fermented with the non-pathogenic fungus Aspergillus oryzae (koji). We have recently revealed that koji contains an abundant amount of glycosylceramide. Intestinal microbes have significant effect on health.

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Although there have been approximately 60 chemical compounds identified as potent fermentation inhibitors in lignocellulose hydrolysate, our research group recently discovered glycolaldehyde as a key fermentation inhibitor during second generation biofuel production. Accordingly, we have developed a yeast S. cerevisiae strain exhibiting tolerance to glycolaldehyde.

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Oxygen, a key nutrient in alcoholic fermentation, is rapidly depleted during this process. Several pathways of oxygen utilization have been reported in the yeast Saccharomyces cerevisiae during alcoholic fermentation, namely synthesis of unsaturated fatty acid, sterols and heme, and the mitochondrial electron transport chain. However, the interaction between these pathways has not been investigated.

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In nature, different microorganisms create communities through their physiochemical and metabolic interactions. Many fermenting microbes, such as yeasts, lactic acid bacteria, and acetic acid bacteria, secrete acidic substances and grow faster at acidic pH values. However, on the surface of cereals, the pH is neutral to alkaline.

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The complex inhibitory effects of inhibitors present in lignocellulose hydrolysate suppress the ethanol fermentation of Saccharomyces cerevisiae. Although the interactive inhibitory effects play important roles in the actual hydrolysate, few studies have investigated glycolaldehyde, the key inhibitor of hot-compressed water-treated lignocellulose hydrolysate. Given this challenge, we investigated the interactive effects of mixed fermentation inhibitors, including glycolaldehyde.

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Research on the relationship between mitochondrial membrane potential and fermentation profile is being intensely pursued because of the potential for developing advanced fermentation technologies. In the present study, we isolated naturally occurring strains of yeast from sake mash that produce high levels of malic acid and demonstrate that variations in mitochondrial membrane potential correlate with malic acid production. To define the underlying biochemical mechanism, we determined the activities of enzymes required for malic acid synthesis and found that pyruvate carboxylase and malate dehydrogenase activities in strains that produce high levels of malic acid were elevated compared with the standard sake strain K901.

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Sake lees are solid parts filtered from the mash of sake, the traditional rice wine of Japan, which is brewed with Aspergillus oryzae and Saccharomyces cerevisiae. The moisture-holding activity of sake lees has long been recognized in Japan. However, the constituent responsible for this activity has not been elucidated.

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Saccharomyces cerevisiae sake yeast strain Kyokai no. 7 has one of the highest fermentation rates among brewery yeasts used worldwide; therefore, it is assumed that it is not possible to enhance its fermentation rate. However, in this study, we found that fermentation by sake yeast can be enhanced by inhibiting mitophagy.

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Mitochondria are sites of oxidative respiration. During sake brewing, sake yeasts are exposed to long periods of hypoxia; the structure, role, and metabolism of mitochondria of sake yeasts have not been studied in detail. It was first elucidated that the mitochondrial structure of sake yeast transforms from filamentous to dotted structure during sake brewing, which affects malate metabolism.

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Although the decrease in pyruvate secretion by brewer's yeasts during fermentation has long been desired in the alcohol beverage industry, rather little is known about the regulation of pyruvate accumulation. In former studies, we developed a pyruvate under-secreting sake yeast by isolating a strain (TCR7) tolerant to ethyl α-transcyanocinnamate, an inhibitor of pyruvate transport into mitochondria. To obtain insights into pyruvate metabolism, in this study, we investigated the mitochondrial activity of TCR7 by oxigraphy and (13) C-metabolic flux analysis during aerobic growth.

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Because of the growing market for sports drinks, prevention of yeast contamination of these beverages is of significant concern. This research was performed to achieve insight into the physiology of yeast growing in sports drinks through a genome-wide approach to prevent microbial spoilage of sports drinks. The genome-wide gene expression profile of Saccharomyces cerevisiae growing in the representative sports drink was investigated.

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Hot-compressed water treatment of lignocellulose liberates numerous inhibitors that prevent ethanol fermentation of yeast Saccharomyces cerevisiae. Glycolaldehyde is one of the strongest fermentation inhibitors and we developed a tolerant strain by overexpressing ADH1 encoding an NADH-dependent reductase; however, its recovery was partial. In this study, to overcome this technical barrier, redox cofactor preference of glycolaldehyde detoxification was investigated.

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Sake is an alcoholic beverage of Japan, with a tradition lasting more than 1,300 years; it is produced from rice and water by fermenting with the koji mold Aspergillus oryzae and sake yeast Saccharomyces cerevisiae. Breeding research on sake yeasts was originally developed in Japan by incorporating microbiological and genetic research methodologies adopted in other scientific areas. Since the advent of a genetic paradigm, isolation of yeast mutants has been a dominant approach for the breeding of favorable sake yeasts.

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