For the discovery of penicillin from this species Alexander Fleming shared the Nobel Prize in Physiology or Medicine in 1945.

[1] The original penicillin-producing type has been variously identified as Penicillium rubrum, P. notatum, and P. chrysogenum among others, but genomic comparison and phylogenetic analysis in 2011 resolved that it is P.

It also produces other important bioactive compounds such as andrastin, chrysogine, fungisporin, roquefortine, and sorbicillins.

[4][5] Belgian microbiologist Philibert Melchior Joseph Ehi Biourge was the first to describe P. rubens in 1923.

[6] The medicinal importance was discovered by Alexander Fleming, a physician at St Mary's Hospital, London.

[10][11] The Seventeenth International Botanical Congress held in Vienna, Austria, in 2005 adopted the name P. chrysogenum as the conserved name (nomen conservandum).

The conidia are smooth-walled, ellipsoidal in shape, measuring 2.5-4.0 μm long, and are blue or bluish-green in colour.

[19] Three genes, namely pcbAB, pcbC, and penDE constitute the core sites for penicillin biosynthesis.

The gene Pch018g00010 that codes for enzymes in glutathione metabolism is considered as the key factor in enhanced penicillin production of this strain.

Enzymes of the final biosynthetic pathway such as acyl-CoA:isopenicillinN acyltransferase28 and phenylacetyl-CoA ligase are synthesised in separate cell organelles called microbodies (peroxisomes).