A Moldy Cantaloupe Makes Penicillin a Wartime Mass-Produced Drug
American pharmaceutical companies and a chance melon in an Illinois market turn Fleming's discovery into millions of doses in time for the invasion of Europe
Quick facts
- Key strain
- Penicillium strain NRRL 1951, from a moldy cantaloupe found in Peoria, Illinois
- Lead companies
- Merck, Squibb, Pfizer, Eli Lilly, Abbott, Upjohn, Parke-Davis
- Coordinating body
- U.S. War Production Board
- Production growth
- Over 250-fold increase in monthly output, May-June 1944
- Milestone
- Enough penicillin for all Allied forces by end of 1943
What happened
After Howard Florey and Ernst Chain proved penicillin worked as a treatment in 1940, the drug still existed only in tiny, painstakingly extracted quantities. Florey traveled to the United States in 1941 to secure help mass-producing it, and the U.S. War Production Board coordinated 21 companies, government agencies, and universities into what researchers later called a unified scientific workforce of mycologists, chemists, and engineers. The key breakthrough came from an unglamorous source: scientists at the Northern Regional Research Laboratory in Peoria, Illinois were collecting mold samples from wherever they could find them, including fruit brought in from local markets, when a moldy cantaloupe yielded a strain, later designated NRRL 1951, that produced far more penicillin than Fleming's original mold and proved ideal for large tank fermentation. Seven major firms, Merck, Squibb, Pfizer, Eli Lilly, Abbott, Upjohn, and Parke-Davis, scaled up production using this strain and deep-tank fermentation techniques, and by the end of 1943 there was enough penicillin to treat all Allied armed forces; monthly production increased more than 250-fold between May and June of 1944 alone, in time to treat wounded troops after the Normandy invasion.
Why it matters
The strain from that single cantaloupe, still called the parent strain of nearly all commercial penicillin production today, shows how a systematic, almost brute-force search, testing whatever mold turned up, solved a problem that pure chemistry could not. Mass-produced penicillin transformed battlefield medicine and, after the war, civilian treatment of bacterial infections that had previously been routinely fatal, from wound infections to pneumonia.
How we know
The wartime production effort is documented in U.S. government and pharmaceutical industry records analyzed in peer-reviewed histories of the penicillin collaborative; the moldy cantaloupe strain's discovery and its designation as NRRL 1951 is corroborated by Science History Institute-affiliated reporting on the Peoria laboratory's records.
Sources
- PMC (National Library of Medicine). Rethinking Antibiotic Research and Development: World War II and the Penicillin Collaborative · Peer-reviewed (author-declared)pmc.ncbi.nlm.nih.gov · Cited as a "journal" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- The Scientist. How a Moldy Cantaloupe Brought Fleming's Penicillin to the World · General sourcethe-scientist.com · Cited as a "news" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
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