British distribution: Ubiquitous throughout Britain in human and natural, terrestrial and freshwater environments
A large form-genus of anamorphic (mitosporic) fungi, their sexual states (teleomorphs), where known, belonging to Eupenicillium or Talaromyces. The genus is best known as the source of the antibiotic penicillin, originally extracted from P. notatum but now obtained commercially, in a number of variants, from strains of P. chrysogenum. The antibiotic griseofulvin is obtained from P. griseofulvum. The genus is also important in cheese manufacture, P. roquefortii being the mould giving the blue veining in cheeses such as Gorganzola and Stilton, while P. camembertii is used in the ripening of soft cheeses such as Camembert and Brie.
However, Penicillium is also part of constant human experience as a regular food spoilage mould, forming velvety, typically blue-grey (to blue or green) mould colonies on bread, rotting fruit, or pretty well any other material capable of being rotted.
The photomicrograph (from the colony pictured above on the salad) shows the chains of conidia (c) borne on brush-like conidiophores (cph). The conidiogenenous cells, the phialides (p) are visible.
Photographed material: typical content of the author's refrigerator, Paisley, 1998.