Aspergillus niger

Aspergillus niger (/ˌæspərˈdʒɪləs/ /ˈnaɪdʒər/) is a mold classified within the Nigri section of the Aspergillus genus. The Aspergillus genus consists of common molds found throughout the environment within soil and water, on vegetation, in fecal matter, on decomposing matter, and suspended in the air. Species within this genus often grow quickly and can sporulate within a few days of germination. A combination of characteristics unique to A. niger makes the microbe invaluable to the production of many acids, proteins and bioactive compounds. Characteristics including extensive metabolic diversity, high production yield, secretion capability, and the ability to conduct post-translational modifications are responsible for A. niger's robust production of secondary metabolites. A. niger's capability to withstand extremely acidic conditions makes it especially important for the industrial production of citric acid.

A. niger causes a disease known as "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 found in indoor environments, where its black colonies can be confused with those of Stachybotrys (species of which have also been called "black mold"). A. niger is classified as generally recognized as safe (GRAS) by the US Food and Drug Administration for use in food production, although the microbe is capable of producing toxins that affect human health.