Editorial

2 pages, 520 KiB

Open AccessEditorial

Traditional and Latest Researches on Aspergillus oryzae and Related Koji Molds

by Yujiro Higuchi and Katsuhiko Kitamoto

J. Fungi 2021, 7(12), 1075; https://doi.org/10.3390/jof7121075 - 14 Dec 2021

Cited by 2 | Viewed by 4811

We would like to thank all the contributors to this Special Issue on Aspergillus oryzae and related Koji molds (https://www [...] Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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Research

Jump to: Editorial, Review

16 pages, 1069 KiB

Open AccessArticle

Intake of Koji Amazake Improves Defecation Frequency in Healthy Adults

by Atsushi Kurahashi, Toshihiko Enomoto, Yoshifumi Oguro, Ayana Kojima-Nakamura, Kazuya Kodaira, Kenichi Watanabe, Nobuhiro Ozaki, Hiroshi Goto and Masao Hirayama

J. Fungi 2021, 7(9), 782; https://doi.org/10.3390/jof7090782 - 21 Sep 2021

Cited by 6 | Viewed by 3439

Abstract

Reportedly, the intake of koji amazake, a beverage made from steamed rice fermented by Aspergillus oryzae, improves defecation frequency. However, its functional ingredients and mechanism of action remain unclear. To compare the effects of koji amazake and a placebo beverage on [...] Read more.

Reportedly, the intake of koji amazake, a beverage made from steamed rice fermented by Aspergillus oryzae, improves defecation frequency. However, its functional ingredients and mechanism of action remain unclear. To compare the effects of koji amazake and a placebo beverage on defecation frequency and to identify the functional ingredients and mechanism of action, a randomized, placebo-controlled, double-blind parallel-group comparative trial was performed on two groups. The koji amazake had 302 ± 15.5 mg/118 g of A. oryzae cells, which was not in the placebo. Compared with the placebo group, the koji amazake group showed a significant increase in weekly defecation frequency at 2 weeks (5.09 days vs. 4.14 days), 3 weeks (5.41 days vs. 4.18 days), and 4 weeks (5.09 days vs. 3.95 days), along with an increase in the weekly fecal weight at 4 weeks (724 g vs. 501 g). The intake of koji amazake did not induce significant intergroup differences in the fecal SCFA concentration, whereas it significantly decreased the relative abundance of Blautia and significantly increased that of Bacteroides at 3 weeks. Therefore, koji amazake intake improved defecation frequency, and A. oryzae cells played potentially important roles as functional ingredients. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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Review

Jump to: Editorial, Research

18 pages, 329 KiB

Open AccessReview

Koji Molds for Japanese Soy Sauce Brewing: Characteristics and Key Enzymes

by Kotaro Ito and Asahi Matsuyama

J. Fungi 2021, 7(8), 658; https://doi.org/10.3390/jof7080658 - 13 Aug 2021

Cited by 38 | Viewed by 8217

Abstract

Soy sauce is a traditional Japanese condiment produced from the fermentation of soybeans, wheat, and salt by three types of microorganisms, namely koji molds, halophilic lactic acid bacteria, and salt-tolerant yeast. The delicate balance between taste, aroma, and color contributes to the characteristic [...] Read more.

Soy sauce is a traditional Japanese condiment produced from the fermentation of soybeans, wheat, and salt by three types of microorganisms, namely koji molds, halophilic lactic acid bacteria, and salt-tolerant yeast. The delicate balance between taste, aroma, and color contributes to the characteristic delicious flavor imparted by soy sauce. In soy sauce brewing, protein and starch of the raw materials are hydrolyzed into amino acids and sugars by enzymes derived from koji molds. These enzymatically hydrolyzed products not only directly contribute to the taste but are further metabolized by lactic acid bacteria and yeasts to most of organic acids and aromatic compounds, resulting in its distinctive flavor and aroma. The color of the soy sauce is also due to the chemical reactions between amino acids and sugars during fermentation. Therefore, koji mold, which produces various enzymes for the breakdown of raw materials, is an essential microorganism in soy sauce production and plays an essential role in fermenting the ingredients. In this review, we describe the manufacturing process of Japanese soy sauce, the characteristics of koji molds that are suitable for soy sauce brewing, and the key enzymes produced by koji molds and their roles in the degradation of materials during soy sauce fermentation, focusing on the production of umami taste in soy sauce brewing. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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11 pages, 3042 KiB

Open AccessReview

Genome Editing Technology and Its Application Potentials in the Industrial Filamentous Fungus Aspergillus oryzae

by Jun-ichi Maruyama

J. Fungi 2021, 7(8), 638; https://doi.org/10.3390/jof7080638 - 05 Aug 2021

Cited by 14 | Viewed by 3603

Abstract

Aspergillus oryzae is a filamentous fungus that has been used in traditional Japanese brewing industries, such as the sake, soy sauce, and miso production. In addition, A. oryzae has been used in heterologous protein production, and the fungus has been recently used in [...] Read more.

Aspergillus oryzae is a filamentous fungus that has been used in traditional Japanese brewing industries, such as the sake, soy sauce, and miso production. In addition, A. oryzae has been used in heterologous protein production, and the fungus has been recently used in biosynthetic research due to its ability to produce a large amount of heterologous natural products by introducing foreign biosynthetic genes. Genetic manipulation, which is important in the functional development of A. oryzae, has mostly been limited to the wild strain RIB40, a genome reference suitable for laboratory analysis. However, there are numerous industrial brewing strains of A. oryzae with various specialized characteristics, and they are used selectively according to the properties required for various purposes such as sake, soy sauce, and miso production. Since the early 2000s, genome editing technologies have been developed; among these technologies, transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) have been applied to gene modification in A. oryzae. Notably, the CRISPR/Cas9 system has dramatically improved the efficiency of gene modification in industrial strains of A. oryzae. In this review, the development of genome editing technology and its application potentials in A. oryzae are summarized. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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17 pages, 2495 KiB

Open AccessReview

Japanese Traditional Miso and Koji Making

by Ken-Ichi Kusumoto, Youhei Yamagata, Rina Tazawa, Manabu Kitagawa, Taeko Kato, Kenji Isobe and Yutaka Kashiwagi

J. Fungi 2021, 7(7), 579; https://doi.org/10.3390/jof7070579 - 20 Jul 2021

Cited by 31 | Viewed by 9015

Abstract

Miso is a traditional Japanese seasoning paste produced by fermenting soybeans using the power of koji mold. A recent Japanese cohort study has shown that increased consumption of fermented soybean products is associated with a reduced risk of death in both men and [...] Read more.

Miso is a traditional Japanese seasoning paste produced by fermenting soybeans using the power of koji mold. A recent Japanese cohort study has shown that increased consumption of fermented soybean products is associated with a reduced risk of death in both men and women. In this review, we briefly explain what miso means in the Japanese culture and food industry, varieties of miso available today, and steps involved in miso making. Then, we review early and latest scientific researches in koji mold species, their safety, and beneficial enzymes they produce during fermentation and maturation processes, which play a major part in determining the quality and sensory profile of miso. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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18 pages, 4728 KiB

Open AccessReview

Koji Starter and Koji World in Japan

by Hideyuki Yamashita

J. Fungi 2021, 7(7), 569; https://doi.org/10.3390/jof7070569 - 16 Jul 2021

Cited by 28 | Viewed by 8578

Abstract

Koji is made by culturing koji mold on grains. Koji has wide-ranging applications, for example, in alcoholic beverages and seasonings. The word ‘mold’ generally has a bad image, but in Japan, koji mold is valued for its usefulness, and over the years, efforts [...] Read more.

Koji is made by culturing koji mold on grains. Koji has wide-ranging applications, for example, in alcoholic beverages and seasonings. The word ‘mold’ generally has a bad image, but in Japan, koji mold is valued for its usefulness, and over the years, efforts have been made to make safe, stable, and delicious food products from it. Koji mold spores, essential when making koji, are called koji starter in the industry. From the many available strains, those suitable for the production of each fermented food are chosen based on indicators such as growth rate and enzyme production capacity. In manufacturing using microorganisms, purity and yield are prioritized. However, the production of fermented foods using koji is more complex, with focus not only on the degree of decomposition of raw materials but also on factors influencing overall product design, including palatability, color, smell, and texture. Production can be facilitated by the variety of koji brought about by the diversity of koji mold combined with the solid culture method which increases the amount of enzyme production. In this report, we introduce the history of koji starter in Japan, the characteristics of koji mold in practice, and various fermented foods made from it. In addition, the factors affecting the quality of koji in solid culture are described. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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17 pages, 1445 KiB

Open AccessReview

Membrane Traffic in Aspergillus oryzae and Related Filamentous Fungi

by Yujiro Higuchi

J. Fungi 2021, 7(7), 534; https://doi.org/10.3390/jof7070534 - 01 Jul 2021

Cited by 15 | Viewed by 3837

Abstract

The industrially important filamentous fungus Aspergillus oryzae, known as the yellow Koji mold and also designated the Japanese National fungus, has been investigated for understanding the intracellular membrane trafficking machinery due to the great ability of valuable enzyme production. The underlying molecular [...] Read more.

The industrially important filamentous fungus Aspergillus oryzae, known as the yellow Koji mold and also designated the Japanese National fungus, has been investigated for understanding the intracellular membrane trafficking machinery due to the great ability of valuable enzyme production. The underlying molecular mechanisms of the secretory pathway delineate the main secretion route from the hyphal tip via the vesicle cluster Spitzenkörper, but also there is a growing body of evidence that septum-directed and unconventional secretion occurs in A. oryzae hyphal cells. Moreover, not only the secretory pathway but also the endocytic pathway is crucial for protein secretion, especially having a role in apical endocytic recycling. As a hallmark of multicellular filamentous fungal cells, endocytic organelles early endosome and vacuole are quite dynamic: the former exhibits constant long-range motility through the hyphal cells and the latter displays pleiomorphic structures in each hyphal region. These characteristics are thought to have physiological roles, such as supporting protein secretion and transporting nutrients. This review summarizes molecular and physiological mechanisms of membrane traffic, i.e., secretory and endocytic pathways, in A. oryzae and related filamentous fungi and describes the further potential for industrial applications. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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10 pages, 964 KiB

Open AccessReview

Making Traditional Japanese Distilled Liquor, Shochu and Awamori, and the Contribution of White and Black Koji Fungi

by Kei Hayashi, Yasuhiro Kajiwara, Taiki Futagami, Masatoshi Goto and Hideharu Takashita

J. Fungi 2021, 7(7), 517; https://doi.org/10.3390/jof7070517 - 28 Jun 2021

Cited by 13 | Viewed by 3727

Abstract

The traditional Japanese single distilled liquor, which uses koji and yeast with designated ingredients, is called “honkaku shochu.” It is made using local agricultural products and has several types, including barley shochu, sweet potato shochu, rice shochu, and buckwheat shochu. In the case [...] Read more.

The traditional Japanese single distilled liquor, which uses koji and yeast with designated ingredients, is called “honkaku shochu.” It is made using local agricultural products and has several types, including barley shochu, sweet potato shochu, rice shochu, and buckwheat shochu. In the case of honkaku shochu, black koji fungus (Aspergillus luchuensis) or white koji fungus (Aspergillus luchuensis mut. kawachii) is used to (1) saccharify the starch contained in the ingredients, (2) produce citric acid to prevent microbial spoilage, and (3) give the liquor its unique flavor. In order to make delicious shochu, when cultivating koji fungus during the shochu production process, we use a unique temperature control method to ensure that these three important elements, which greatly affect the taste of the produced liquor, are balanced without any excess or deficiency. This review describes in detail the production method of honkaku shochu, a distilled spirit unique to Japan and whose market is expected to expand worldwide, with special attention paid to the koji fungi cultivation step. Furthermore, we describe the history of the koji fungi used today in the production of shochu, and we provide a thorough explanation of the characteristics of each koji fungi. We also report the latest research progress on this topic. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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10 pages, 2652 KiB

Open AccessReview

Reconstitution of Polyketide-Derived Meroterpenoid Biosynthetic Pathway in Aspergillus oryzae

by Takayoshi Awakawa and Ikuro Abe

J. Fungi 2021, 7(6), 486; https://doi.org/10.3390/jof7060486 - 16 Jun 2021

Cited by 14 | Viewed by 3175

Abstract

The heterologous gene expression system with Aspergillus oryzae as the host is an effective method to investigate fungal secondary metabolite biosynthetic pathways for reconstruction to produce un-natural molecules due to its high productivity and genetic tractability. In this review, we focus on biosynthetic [...] Read more.

The heterologous gene expression system with Aspergillus oryzae as the host is an effective method to investigate fungal secondary metabolite biosynthetic pathways for reconstruction to produce un-natural molecules due to its high productivity and genetic tractability. In this review, we focus on biosynthetic studies of fungal polyketide-derived meroterpenoids, a group of bioactive natural products, by means of the A. oryzae heterologous expression system. The heterologous expression methods and the biosynthetic reactions are described in detail for future prospects to create un-natural molecules via biosynthetic re-design. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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10 pages, 1130 KiB

Open AccessReview

Ingredients, Functionality, and Safety of the Japanese Traditional Sweet Drink Amazake

by Atsushi Kurahashi

J. Fungi 2021, 7(6), 469; https://doi.org/10.3390/jof7060469 - 10 Jun 2021

Cited by 14 | Viewed by 5428

Abstract

The sweet drink amazake is a fermented food made from Aspergillus oryzae and related koji molds in Japan. There are two types of drinks called amazake, one made from koji (koji amazake) and the other made from sake lees, a [...] Read more.

The sweet drink amazake is a fermented food made from Aspergillus oryzae and related koji molds in Japan. There are two types of drinks called amazake, one made from koji (koji amazake) and the other made from sake lees, a by-product of sake (sakekasu amazake). The sweetness of koji amazake is from glucose, derived from starch broken down by A. oryzae amylase. The other, sakekasu amazake, depends on added sugar. The main components are glucose and sucrose, but they also contain more than 300 other ingredients. Koji amazake contains oligosaccharides and ergothioneine, and sakekasu amazake has a resistant protein and α-ethyl glucoside, which are characteristic ingredients of each amazake. However, there are also common ingredients such as glycosylceramide. Functionality is known to include anti-fatigue, bowel movement, skin barrier, and other effects on human health. In particular, the bowel movement-improving effects have been well studied for both amazakes. These functions result from ingesting approximately 100 mL per day, but human clinical trials have clarified that this amount has no effect on blood glucose levels and weight gain. In the future, the identification of substances associated with each function is required. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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14 pages, 26168 KiB

Open AccessReview

Medical Application of Substances Derived from Non-Pathogenic Fungi Aspergillus oryzae and A. luchuensis-Containing Koji

by Hiroshi Kitagaki

J. Fungi 2021, 7(4), 243; https://doi.org/10.3390/jof7040243 - 24 Mar 2021

Cited by 18 | Viewed by 6326

Abstract

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 koji fermented with non-pathogenic fungus Aspergillus oryzae for more than 1300 [...] Read more.

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 koji fermented with non-pathogenic fungus Aspergillus oryzae for more than 1300 years. Recent research has elucidated that koji contains medicinal substances such as Taka-diastase, acid protease, koji glycosylceramide, kojic acid, oligosaccharides, ethyl-α-d-glucoside, ferulic acid, ergothioneine, pyroglutamyl leucine, pyranonigrin A, resistant proteins, deferriferrichrysin, polyamines, Bifidobacterium-stimulating peptides, angiotensin I-converting enzyme inhibitor peptides, 14-dehydroergosterol, beta-glucan, biotin, and citric acid. This review introduces potential medical applications of such medicinal substances to hyperlipidemia, diabetes, hypertension, cardiovascular and cognitive diseases, chronic inflammation, epidermal permeability barrier disruption, coronavirus disease 2019 (COVID-19), and anti-cancer therapy. Full article

(This article belongs to the Special Issue Aspergillus oryzae and related Koji molds)

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