Aspergillus oryzae
Encyclopedia
Aspergillus oryzae is a filamentous
fungus
(a mold
). It is used in Chinese
and Japanese cuisine
to ferment
soybean
s. It is also used to saccharify rice, other grains
, and potato
es in the making of alcoholic beverage
s such as huangjiu
, sake, and shōchū
. The domestication
of A. oryzae occurred at least two thousand years ago. A. oryzae is used for the production of rice vinegar
s.
Dr. Eiji Ichishima of Tohoku University called the kōji fungus a "national fungus" ("kokkin") in the journal of the Brewing Society of Japan, because of its importance not only for making the koji for sake brewing but also for making the koji for miso
, soy sauce
and a range of other traditional Japanese foods. His proposal was approved at the society's annual meeting in 2006.
"Red kōji-kin" is a separate species, Monascus purpureus
.
was released by a consortium of Japanese biotechnology companies in late 2005. The eight chromosome
s together comprise 37 million base pair
s and twelve thousand predicted gene
s. The genome of A. oryzae is thus one-third larger than that of two related Aspergillus
species, the genetics model organism Aspergillus nidulans
and the potentially dangerous Aspergillus fumigatus
. Many of the extra genes present in A. oryzae are predicted to be involved in secondary metabolism
. The sequenced strain was isolated in 1950 and is called RIB40 or ATCC
42149; its morphology, growth, and enzyme production are typical of strains used for sake brewing.
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
(a mold
Mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
). It is used in Chinese
Chinese cuisine
Chinese cuisine is any of several styles originating in the regions of China, some of which have become highly popular in other parts of the world – from Asia to the Americas, Australia, Western Europe and Southern Africa...
and Japanese cuisine
Japanese cuisine
Japanese cuisine has developed over the centuries as a result of many political and social changes throughout Japan. The cuisine eventually changed with the advent of the Medieval age which ushered in a shedding of elitism with the age of shogun rule...
to ferment
Fermentation (food)
Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugars into ethanol...
soybean
Soybean
The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...
s. It is also used to saccharify rice, other grains
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
, and potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
es in the making of alcoholic beverage
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...
s such as huangjiu
Huangjiu
Huangjiu is a type of Chinese beverage brewed directly from grains such as rice, millet, or wheat. Unlike baijiu, such liquors are not distilled, and contain less than 20% alcohol, due to the inhibition of fermentation by ethanol at that concentration...
, sake, and shōchū
Shochu
is a Japanese distilled beverage. It is typically distilled from barley, sweet potatoes, or rice, though it is sometimes produced from other ingredients such as brown sugar, buckwheat or chestnut. Typically shōchū contains 25% alcohol by volume...
. The domestication
Domestication
Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been...
of A. oryzae occurred at least two thousand years ago. A. oryzae is used for the production of rice vinegar
Rice vinegar
Rice vinegar is a vinegar made from fermented rice or rice wine in China, Japan, Korea, and Vietnam.-Chinese:Chinese rice vinegars are stronger than Japanese ones, and range in colour from clear to various shades of red and brown...
s.
Dr. Eiji Ichishima of Tohoku University called the kōji fungus a "national fungus" ("kokkin") in the journal of the Brewing Society of Japan, because of its importance not only for making the koji for sake brewing but also for making the koji for miso
Miso
is a traditional Japanese seasoning produced by fermenting rice, barley and/or soybeans, with salt and the fungus , the most typical miso being made with soy. The result is a thick paste used for sauces and spreads, pickling vegetables or meats, and mixing with dashi soup stock to serve as miso...
, soy sauce
Soy sauce
Soy sauce is a condiment produced by fermenting soybeans with Aspergillus oryzae or Aspergillus sojae molds, along with water and salt...
and a range of other traditional Japanese foods. His proposal was approved at the society's annual meeting in 2006.
"Red kōji-kin" is a separate species, Monascus purpureus
Monascus purpureus
Monascus purpureus is a species of mold that is purplish-red in color...
.
Properties desirable in sake brewing and testing
The following properties of A. oryzae strains are important in rice saccharification for sake brewing:- Growth: rapid mycelialMyceliumthumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
growth on and into the rice kernels - Enzymes: strong secretion of amylaseAmylaseAmylase is an enzyme that catalyses the breakdown of starch into sugars. Amylase is present in human saliva, where it begins the chemical process of digestion. Food that contains much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns...
s (α-amylaseAlpha-Amylaseα-Amylase is an enzyme that hydrolyses alpha-bonds of large alpha-linked polysaccharides such as starch and glycogen, yielding glucose and maltose. It is the major form of amylase found in humans and other mammals...
and glucoamylase); some carboxypeptidaseCarboxypeptidaseA carboxypeptidase is a protease enzyme that hydrolyzes the peptide bond of an amino acid residue at the carboxy-terminal end...
; low tyrosinaseTyrosinaseTyrosinase also known as monophenol monooxygenase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals... - Aesthetics: pleasant fragrance; accumulation of flavoring compounds
- Color: low production of deferriferrichrome (a siderophoreSiderophoreSiderophores are small, high-affinity iron chelating compounds secreted by grasses and microorganisms such as bacteria and fungi...
), flavins, and other colored substances
Genome
Initially kept secret, the A. oryzae genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
was released by a consortium of Japanese biotechnology companies in late 2005. The eight chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s together comprise 37 million base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
s and twelve thousand predicted gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s. The genome of A. oryzae is thus one-third larger than that of two related Aspergillus
Aspergillus
Aspergillus is a genus consisting of several hundred mold species found in various climates worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli...
species, the genetics model organism Aspergillus nidulans
Aspergillus nidulans
Aspergillus nidulans is one of many species of filamentous fungi in the phylum Ascomycota...
and the potentially dangerous Aspergillus fumigatus
Aspergillus fumigatus
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency....
. Many of the extra genes present in A. oryzae are predicted to be involved in secondary metabolism
Secondary metabolite
Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism. Unlike primary metabolites, absence of secondary metabolities does not result in immediate death, but rather in long-term impairment of the organism's...
. The sequenced strain was isolated in 1950 and is called RIB40 or ATCC
American Type Culture Collection
The American Type Culture Collection is a private, not-for-profit biological resource center whose mission focuses on the acquisition, authentication, production, preservation, development and distribution of standard reference microorganisms, cell lines and other materials for research in the...
42149; its morphology, growth, and enzyme production are typical of strains used for sake brewing.
In fiction
A. oryzae is a supporting character (of sorts) in the manga series Moyasimon: Tales of Agriculture and its anime adaptation.External links
- Sake World's description of koji
- Aspergillus oryzae genome from the Database of Genomes Analysed at NITE (DOGAN)
- Koji, an Aspergillus, by Fujita, Chieko, Tokyo Foundation