Penicillium

Penicillium (/ˌpɛnɪˈsɪliəm/) ascomycetous fungi are of major importance in the natural environment as well as food and drug production. Some members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria. Other species are used in cheesemaking. According to the Dictionary of the Fungi (10th edition, 2008), the widespread genus contains over 300 species. The genus was first described in the scientific literature by Johann Heinrich Friedrich Link in his 1809 work Observationes in ordines plantarum naturales, writing 'Penicillium. Thallus e floccis caespitosis septatis simplicibus aut ramosis fertilibus erectis apice penicillatis', where penicillatis referred to 'pencil-like' (referring to a Camel's hair pencil brush. Link included three species—P. candidum, P. expansum, and P. glaucum—all of which produced a brush-like conidiophore (asexual fruiting structure). The common apple rot fungus P. expansum was selected as the type species. In a 1979 monograph, John I. Pitt divided Penicillium into four subgenera based on conidiophore morphology and branching pattern: Aspergilloides, Biverticillium, Furcatum, and Penicillium.