Aspergillus is a genus of filamentous fungi belonging to Deuteromycetes. Fungi in this genus are easy to grow; some produce a wide range of useful enzymes, but others are dangerous pests and pathogens. For instance, A. niger is used to produce citric acid, gluconic acid, amylase, proteases, and peptic enzymes, but A. parasiticus grows on grains and produces aflatoxin, a powerful liver carcinogen.