Penicillium

Penicillium is a genus of mold fungi in the family Trichocomaceae, within the order Eurotiales of the phylum Ascomycota. Members are widespread in soils, on decaying vegetation, and in indoor environments, and they are commonly found on spoiled food products. They form gray-green to blue-green colonies with brush-like conidiophores that bear chains of conidia, giving the group its characteristic appearance. Reproduction is predominantly asexual, producing conidia on penicillus structures; many species also have sexual stages referred to as Eupenicillium or Talaromyces under older classifications.

The genus has broad ecological and practical significance. Penicillium chrysogenum (historically linked to P. notatum) is the source of penicillin and related beta-lactam antibiotics, a landmark discovery in medicine. Penicillium roqueforti and Penicillium camemberti are used in the production of blue cheeses and soft rind cheeses, respectively, contributing to flavor and texture. Some species spoil fruit and stored products, producing mycotoxins such as patulin (Penicillium expansum) and ochratoxin A (Penicillium verrucosum or Penicillium nordicum), which pose food-safety concerns.

Notable species can also affect stored grains or citrus fruits and are studied for their roles in spoilage, mycotoxin production, and industrial biotechnology. The genus is widely studied in mycology, food safety, and biotechnology due to its roles in antibiotic production, food fermentation, and enzyme development.