Penicillium is a genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of ascomycetous
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 of major importance in the natural environment as well as food and drug production. Members of the genus produce penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

, a molecule that is used as an antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

, which kills or stops the growth of certain kinds of bacteria inside the body. 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
Johann Heinrich Friedrich Link
Johann Heinrich Friedrich Link was a German naturalist and botanist.Link was born at Hildesheim as a son of the minister August Heinrich Link , who taught him the love for nature through collection of 'natural objects'...

 in his 1809 work Observationes in ordines plantarum naturales.