The Molds That Built the Modern World

It's easy to think of mold as a pest. It's also one of the most productive collaborators in human history.

Penicillin (1928)

In 1928, Alexander Fleming noticed that a Penicillium mold contaminating a bacterial culture plate had left a clear ring where bacteria couldn't grow. Howard Florey, Ernst Chain and colleagues turned the observation into a usable drug in the early 1940s, and the three shared the 1945 Nobel Prize. Penicillin has saved countless lives, and the antibiotic era grew from a moldy dish.

Statins

The first statin lead, compactin, was isolated from a Penicillium mold by Akira Endo in the 1970s. Statins are now among the most widely prescribed drugs in the world.

Cyclosporine

The immunosuppressant that made organ transplants practical came from a fungus, Tolypocladium inflatum, found in a Norwegian soil sample.

Koji and fermentation

For roughly two thousand years, East Asian cuisines have used Aspergillus oryzae ("koji") to ferment rice, soybeans and wheat into soy sauce, miso and sake. It's a domesticated mold, as selectively bred as a dog breed, and a close relative of the aflatoxin-producing A. flavus, but it doesn't make aflatoxin, a trait of generations of domestication.

Cheese and charcuterie

Roquefort, Stilton and Gorgonzola use Penicillium roqueforti; Brie and Camembert use P. camemberti. Dry-cured salamis are traditionally coated with edible mold that protects against less desirable ones.

Mycoprotein

Fusarium venenatum, grown in fermenters, is the base of mycoprotein meat alternatives sold since the 1980s.

The lesson

Molds are chemists. Their ability to make potent compounds is exactly why some are medicines, some are foods and a few are toxins. The same chemical creativity that makes aflatoxin makes penicillin. What separates the benefit from the risk is context: which species, which conditions, and whether it's growing where you chose to put it. For the other side of the ledger, see Mycotoxins Explained and the macro view.