Aspergillus niger

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, apricots, 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 mold'). Some strains of A. niger have been reported to produce potent mycotoxins called ochratoxins; 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. It also produces the isoflavone orobol. Aspergillus 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. A number of morphologically similar species were in 2004 described by Samson et al. In 2007 the strain of ATCC 16404 Aspergillus niger was reclassified as Aspergillus brasiliensis (refer to publication by Varga et al.). This has required an update to the U.S. Pharmacopoeia and the European Pharmacopoeia which commonly use this strain throughout the pharmaceutical industry. Aspergillus niger causes black mold of onions and ornamental plants. 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. Aspergillus niger is less likely to cause human disease than some other Aspergillus species. In extremely rare instances, humans may become ill, but this is due to a serious lung disease, aspergillosis, that can occur. Aspergillosis is, in particular, frequent among horticultural workers who inhale peat dust, which can be rich in Aspergillus spores. It has been found in the mummies of ancient Egyptian tombs and can be inhaled when they are disturbed. Aspergillus niger is one of the most common causes of otomycosis (fungal ear infections), which can cause pain, temporary hearing loss, and, only in severe cases, damage to the ear canal and tympanic membrane.