The genus Penicillium contains over 300 species. Only a few are known to produce penicillins [1] , including P. griseofulvum, P. dipodomys, P. flavigenum, P. nalgiovense, P. chrysogenum and notably P. rubens [2] , the strain with which Fleming made his famous discovery.
From Biology
The main cheese-making Penicilliums – roqueforti (blue cheese), camemberti, (Camembert and Brie) and glaucum (Gorgonzola) – are not penicillin producers. They do produce other antibacterial metabolites – as well as human toxins and allergens – but no medically useful antibiotics.
P. chrysogenum, From Penicillium chrysogenum – NBRC 32030 – CHỦNG VI SINH VẬT CHUẨN ATCC
Even if you ate cheese bearing a penicillin-producing strain, you would get no medical benefit. The dose would be too small, and what little you ingested would be quickly degraded in stomach acid.
The orally-active “natural” penicillins – Penicillins G and V – are produced by growing P. chrysogenum in culture medium to which phenylacetic or phenoxyacetic acid, respectively, have been added [3] . These molecules are incorporated into penicillin and render it more acid-resistant.
Aside from antibiotic production, fungi such as Penicillium species are found in the gut microbiome [4] , and presumably could have beneficial or harmful effects. We don’t really know enough about the gut “mycobiome” to say.
However, Penicillium species are not prevalent (Saccharomyces, Malassezia, and Candida dominate), and probably do not stably colonize the gut [5] – they don’t grow at body temperature. Caves filled with milk products are their preferred habitat.
There is no reliable evidence of any health benefits from eating blue cheese. One report claims that highly ripened cheeses inhibit proliferation of leukemia cells in Petri dishes [6] , but that is no kind of evidence that these cheeses prevent cancer. Other studies show that cheeses produce anti-inflammatories and the polyamine spermidine, but the dots between these tidbits of information and actual health outcomes have not been connected.
After all, we all know that carrots are good for you and carrots are full of beta-carotene. Beta-carotene is a powerful anti-inflammatory and prevents cancer in lab studies, but when tested in humans it was found to increase cancer and overall mortality.
Blue cheese is delicious and so are carrots. They both deserve to be appreciated for what they are, to be enjoyed in moderation, and not to be hyped by credulous true-believers or cynical scammers.
Footnotes
[1] Production of Penicillin by Fungi Growing on Food Products: Identification of a Complete Penicillin Gene Cluster in Penicillium griseofulvum and a Truncated Cluster in Penicillium verrucosum
[2] Fleming’s penicillin producing strain is not Penicillium chrysogenum but P. rubens
[3] The Natural Penicillins — Benzylpenicillin (Penicillin G) and Phenoxymethylpenicillin (Penicillin V)
[4] The gut mycobiome of the Human Microbiome Project healthy cohort
[5] Fungi in the healthy human gastrointestinal tract
[6] Effects of highly ripened cheeses on HL-60 human leukemia cells: antiproliferative activity and induction of apoptotic DNA damage.