Aspergillus niger

Aspergillus niger

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Encyclopedia
Aspergillus niger is a 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...

 and one of the most common species of the genus 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...

. It causes a disease called black mold on certain fruits and vegetables such as grapes, onions, and peanuts, and is a common contaminant of food. It is ubiquitous in soil and is commonly reported from indoor environments, where its black colonies can be confused with those of Stachybotrys
Stachybotrys
Stachybotrys is a genus of molds, or asexually-reproducing, filamentous fungi. Closely related to the genus Memnoniella, most Stachybotrys species inhabit materials rich in cellulose. The genus has a widespread distribution, and contains about 50 species.The most infamous species, S. chartarum and S...

(species of which have also been called "black mould").

Some strains of A. niger have been reported to produce potent mycotoxin
Mycotoxin
A mycotoxin is a toxic secondary metabolite produced by organisms of the fungus kingdom, commonly known as molds. The term ‘mycotoxin’ is usually reserved for the toxic chemical products produced by fungi that readily colonize crops...

s called ochratoxin
Ochratoxin
Ochratoxins are a group of mycotoxins produced by some Aspergillus species and Penicillium species including Aspergillus ochraceus and Penicillium viridicatum...

s, but other sources disagree, claiming this report is based upon misidentification of the fungal species. Recent evidence suggests some true A. niger strains do produce ochratoxin A
Ochratoxin A
Ochratoxin A, a toxin produced by Aspergillus ochraceus, Aspergillus carbonarius and Penicillium verrucosum, is one of the most abundant food-contaminating mycotoxins in the world. Human exposure occurs mainly through consumption of improperly stored food products, particularly contaminated grain...

.

Taxonomy


A. niger is included in 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...

subgenus Circumdati, section Nigri. The section Nigri includes 15 related black-spored species that may be confused with A. niger, including A. tubingensis, A. foetidus, A. carbonarius, and A. awamori. A number of morphologically similar species were recently described by Samson et al.

Plant disease


A. niger causes black mold of onions. Infection of onion seedlings by A. niger can become systemic, manifesting only when conditions are conducive. A. niger causes a common postharvest disease of onions, in which the black conidia can be observed between the scales of the bulb. The fungus also causes disease in peanuts and in grapes.

Human and animal disease


A. niger is less likely to cause human disease than some other Aspergillus species, but, if large amounts of spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s are inhaled, a serious lung disease, aspergillosis
Aspergillosis
Aspergillosis is the name given to a wide variety of diseases caused by fungi of the genus Aspergillus. The most common forms are allergic bronchopulmonary aspergillosis, pulmonary aspergilloma and invasive aspergillosis. Most humans inhale Aspergillus spores every day...

 can occur. Aspergillosis is, in particular, frequent among horticultural
Horticulture
Horticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic...

 workers that inhale peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

 dust, which can be rich in Aspergillus spores. It has been found on the walls of ancient Egyptian tombs and can be inhaled when the area is disturbed. A. niger is one of the most common causes of otomycosis
Otomycosis
Otomycosis is a fungal ear infection, a superficial mycotic infection of the outer ear canal. It is more common in the tropical countries. The infection may be either subacute or acute and is characterized by inflammation, pruritus, scaling, and severe discomfort...

 (fungal ear infections), which can cause pain, temporary hearing loss, and, in severe cases, damage to the ear canal
Ear canal
The ear canal , is a tube running from the outer ear to the middle ear. The human ear canal extends from the pinna to the eardrum and is about 35 mm in length and 5 to 10 mm in diameter....

 and tympanic membrane.

Industrial uses


A. niger is cultured for the industrial production of many substances. Various strains of A. niger are used in the industrial preparation of citric acid
Citric acid
Citric acid is a weak organic acid. It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks...

 (E330) and gluconic acid
Gluconic acid
Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH24COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid....

 (E574) and have been assessed as acceptable for daily intake by the World Health Organisation. A. niger fermentation is "generally recognized as safe" (GRAS
Gras
Gras is a commune in the Ardèche department in southern France.-Population:-References:*...

) by the United States Food and Drug Administration under the Federal Food, Drug, and Cosmetic Act
Federal Food, Drug, and Cosmetic Act
The United States Federal Food, Drug, and Cosmetic Act , is a set of laws passed by Congress in 1938 giving authority to the U.S. Food and Drug Administration to oversee the safety of food, drugs, and cosmetics. A principal author of this law was Royal S. Copeland, a three-term U.S. Senator from...

.

Many useful enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s are produced using industrial fermentation of A. niger. For example, A. niger glucoamylase is used in the production of high fructose corn syrup
High fructose corn syrup
High-fructose corn syrup  — also called glucose-fructose syrup in the UK, glucose/fructose in Canada, and high-fructose maize syrup in other countries — comprises any of a group of corn syrups that has undergone enzymatic processing to convert some of its glucose into fructose to produce...

, and pectinase
Pectinase
Pectinase is a general term for enzymes, such as pectolyase, pectozyme and polygalacturonase, commonly referred to in brewing as pectic enzymes. These break down pectin, a polysaccharide substrate that is found in the cell walls of plants. One of the most studied and widely used commercial...

s are used in cider and wine clarification. α-galactosidase
Alpha-galactosidase
Alpha-galactosidase is a glycoside hydrolase enzyme that hydrolyses the terminal alpha-galactosyl moieties from glycolipids and glycoproteins. It is encoded by the gene.- Function :...

, an enzyme that breaks down certain complex sugars, is a component of Beano
Beano (dietary supplement)
Beano is an enzyme-based dietary supplement that is used to reduce gas in the digestive tract, thereby improving digestion and reducing bloating, discomfort, and flatulence caused by gas. It contains the enzyme alpha galactosidase that breaks down oligosaccharides such as raffinose...

 and other medications which the manufacturers claim can decrease flatulence. Another use for A. niger within the biotechnology industry is in the production of magnetic isotope-containing variants of biological macromolecule
Macromolecule
A macromolecule is a very large molecule commonly created by some form of polymerization. In biochemistry, the term is applied to the four conventional biopolymers , as well as non-polymeric molecules with large molecular mass such as macrocycles...

s for NMR
NMR spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained...

 analysis.

Other uses


In 2006 it was reported that a secreted RNase produced by A. niger called actibind
Actibind
Actibind is an actin-binding fungal T-RNase protein that is produced by the black mold Aspergillus niger, a microorganism used in biotechnology and food technology. In plants, actibind binds actin, a major component of the cytoskeleton, interfering with the plants' pollen tubes and halting cell...

has antiangiogenic
Angiogenesis
Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. Though there has been some debate over terminology, vasculogenesis is the term used for spontaneous blood-vessel formation, and intussusception is the term for the formation of new blood...

 and anticarcinogenic
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...

 characteristics.

A. niger is also cultured for the extraction of the enzymes glucose oxidase
Glucose oxidase
The glucose oxidase enzyme is an oxido-reductase that catalyses the oxidation of glucose to hydrogen peroxide and D-glucono-δ-lactone. In cells, it aids in breaking the sugar down into its metabolites....

 (GO) and Alpha-galactosidase
Alpha-galactosidase
Alpha-galactosidase is a glycoside hydrolase enzyme that hydrolyses the terminal alpha-galactosyl moieties from glycolipids and glycoproteins. It is encoded by the gene.- Function :...

 (AGS). Glucose oxidase is used in the design of glucose biosensor
Biosensor
A biosensor is an analytical device for the detection of an analyte that combines a biological component with a physicochemical detector component.It consists of 3 parts:* the sensitive biological element A biosensor is an analytical device for the detection of an analyte that combines a biological...

s, due to its high affinity for β-D-glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

. Alpha-galactosidase can be produced by A. niger fermentation; it is used to hydrolyze alpha 1-6 bonds found in melibiose
Melibiose
Melibiose is a reducing disaccharide formed by an alpha-1,6 linkage between galactose and glucose . It can be formed by invertase mediated hydrolysis of raffinose, which produces melibiose and fructose. Melibiose can be broken down into its component saccharides, glucose and galactose, by the...

, raffinose
Raffinose
Raffinose is a trisaccharide composed of galactose, fructose, and glucose. It can be found in beans, cabbage, brussels sprouts, broccoli, asparagus, other vegetables, and whole grains. Raffinose can be hydrolyzed to D-galactose and sucrose by the enzyme α-galactosidase , an enzyme not found in the...

, and stachyose
Stachyose
Stachyose is a tetrasaccharide consisting of two α--galactose units, one α--glucose unit, and one β--fructose unit sequentially linked as galgalglcfru. Stachyose is naturally found in numerous vegetables and plants.Stachyose is less sweet than sucrose, at about 28% on a weight basis...

.

Research published in 2006-2008 investigated A. niger prolyl endoprotease (AN-PEP), a microbial-derived prolyl endoprotease which cleaves gluten. This has strong implications in the treatment of coeliac disease
Coeliac disease
Coeliac disease , is an autoimmune disorder of the small intestine that occurs in genetically predisposed people of all ages from middle infancy onward...

 or other metabolic gluten sensitivity disease processes. A placebo controlled, double blind study was initiated in December 2008 to determine the efficacy of this enzyme in treating humans with coeliac disease.

In the heyday of the opium
Opium
Opium is the dried latex obtained from the opium poppy . Opium contains up to 12% morphine, an alkaloid, which is frequently processed chemically to produce heroin for the illegal drug trade. The latex also includes codeine and non-narcotic alkaloids such as papaverine, thebaine and noscapine...

 trade, chandoo opium, which was meant to be smoked, was made by long term fermentation of A. niger and other molds on raw opium.

A. niger is the main agent in the fermentation of Pu-erh tea
Pu-erh tea
Pu'er, Pu-erh, Puer, also Po Lei or Bolay is a variety of post-fermented tea produced in Yunnan province, China. Post-fermentation is a tea production style in which the tea leaves undergo a microbial fermentation process after they are dried and rolled. This is a Chinese specialty and is sometimes...

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