Illustration of Penicillin

1928 Penicillin

The book of science

Tom Sharp

Alexander Fleming pharmacology Illustration of Penicillin


A blue-green mold accidentally contaminated Alexander Fleming’s petri dish in which he was growing Staphylococcus bacteria. Strangely, he noticed a halo around the mold in which the bacteria did not grow and studied the matter further, finding that the mold was a Penicillium and that a filtrate of its broth, which he called penicillin, inhibited the growth and broke down the cells of bacteria.


Fleming thought that penicillin might make a good antiseptic but would not survive in the human body long enough to kill pathogenic bacteria. Trials of penicillin to treat humans failed because of the difficulty of purifying it and producing it in sufficient quantities. In 1942, Merk & Co. in the U.S. produced only enough penicillin to treat ten patients. But larger supplies were needed for the war effort. A world-wide search was made for the best source. Fermentation of corn steep liquor and a moldy cantaloupe found in Peoria helped the U.S. produce millions of doses in time for the invasion of Normandy in the spring of 1944.

Painter’s brush

Chains of Penicillium’s conidia resemble a broom. A new broom sweeps corners clean. A painter sweeps his brush across the canvas to represent our dirty world. He paints a portrait of a scientist; he paints an allegory of accidental discovery. An old broom sits in the corner of the view, symbolizing our struggle to live in the natural world.

Fungi, including mushrooms and yeasts used in making bread and beer, are more closely related to animals than to plants. From various fungi, we derive antibiotics, antifungal agents, anti-cholesterol statins, immunosuppressants, alkaloids for the treatment of migranes, and hallucigens. Penicillium is a genus of fungi named after the Latin for “painter’s brush.”

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