| Aspergillus niger | |
|---|---|
| Micrograph of A. niger grown on Sabouraud agar medium. 100x magnification. | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Phylum: | Ascomycota |
| Subphylum: | Pezizomycotina |
| Class: | Eurotiomycetes |
| Order: | Eurotiales |
| Family: | Trichocomaceae |
| Genus: | Aspergillus |
| Species: | A. niger |
| Binomial name | |
| Aspergillus niger van Tieghem 1867 |
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| Synonyms | |
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Aspergillus niger var. niger |
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Aspergillus niger is a fungus and one of the most common species of the genus Aspergillus. 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 (species of which have also been called "black mould").[1]
Some strains of A. niger have been reported to produce potent mycotoxins called ochratoxins,[2] 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.[1][3] It also produces the isoflavone orobol.
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Contents
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A. niger is included in Aspergillus 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.[4][5] A number of morphologically similar species were recently described by Samson et al.[5]
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.
A. niger is less likely to cause human disease than some other Aspergillus species, but, if large amounts of spores are inhaled, a serious lung disease, aspergillosis can occur. Aspergillosis is, in particular, frequent among horticultural workers that inhale peat 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.[citation needed] A. niger is one of the most common causes of otomycosis (fungal ear infections), which can cause pain, temporary hearing loss, and, in severe cases, damage to the ear canal and tympanic membrane.
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 (E330) and gluconic 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) by the United States Food and Drug Administration under the Federal Food, Drug, and Cosmetic Act.[6]
Many useful enzymes are produced using industrial fermentation of A. niger. For example, A. niger glucoamylase is used in the production of high fructose corn syrup, and pectinases are used in cider and wine clarification. α-galactosidase, an enzyme that breaks down certain complex sugars, is a component of Beano 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 macromolecules for NMR analysis.
A. niger is the main agent in the fermentation of Pu-erh tea,[7] the Okinawan awamori spirit, and some varieties of shochu.[8]
In 2006 it was reported that a secreted RNase produced by A. niger called actibind has antiangiogenic and anticarcinogenic characteristics.
A. niger is also cultured for the extraction of the enzymes glucose oxidase (GO) and Alpha-galactosidase (AGS). Glucose oxidase is used in the design of glucose biosensors, due to its high affinity for β-D-glucose.[9] Alpha-galactosidase can be produced by A. niger fermentation; it is used to hydrolyze alpha 1-6 bonds found in melibiose, raffinose, and stachyose.
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 or other metabolic gluten sensitivity disease processes.[10] A placebo controlled, double blind study was initiated in December 2008 to determine the efficacy of this enzyme in treating humans with coeliac disease.[11]
In the heyday of the opium trade, chandoo opium, which was meant to be smoked, was made by long term fermentation of A. niger and other molds on raw opium.[12]
The genomes of two different A. niger strains have been fully sequenced.[13][14]
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