Aspergillus

Aspergillus is a genus of filamentous fungi in the phylum Ascomycota. It is widely distributed in soil, decaying vegetation, and indoor environments. Species are typically saprotrophic and play a role in nutrient cycling. They reproduce asexually by producing conidia on conidiophores; many species form rapid, pigmented colonies with distinctive textures.

Common species include A. fumigatus, A. flavus, and A. niger. Colony color varies by species: A. fumigatus is green to blue-green, A. flavus is yellow-green, and A. niger is black. Spores can become airborne, and inhalation is a common route of exposure.

Ecology and industry: Some species are used in fermentation and biotechnology. Aspergillus oryzae is used in traditional East Asian fermentation (koji) for foods like soy sauce and sake; A. niger is used for citric acid production and enzyme manufacture. Other species produce industrial enzymes, organic acids, and secondary metabolites.

Health relevance: Exposure can cause disease in humans, especially in immunocompromised individuals. Aspergillosis encompasses invasive infections, aspergilloma in preexisting lung cavities, and allergic conditions such as allergic bronchopulmonary aspergillosis. Some species produce mycotoxins; most notably, aflatoxins produced by A. flavus and A. parasiticus pose food-safety concerns and have hepatocarcinogenic potential.

Taxonomy and diversity: The genus contains many species with clinical, agricultural, and industrial relevance. Identification relies on a combination of morphology, growth characteristics, and molecular methods.