Physician and microbiologist Sir Alexander Fleming accidentally discovered penicillin on this day in 1928. Fleming had been studying a specific bacteria but left town for a while. When he came back, he found that one of his sample containers had been left open, that some blue-green Penicillium mold had formed in it, and that the bacteria near the growing fungus were dead. With more experimentation he found that the mold contained a bacteria-killing substance that he dubbed penicillin.
Several cultures around the world had already found mold helped fight some forms of bacteria, but nobody had put their finger on exactly how that worked or how to replicate the process. Fleming isolated penicillin and found it could kill the bacteria that cause staph infections, strep throat, and diphtheria.
You can learn more about Fleming’s discovery at the American Chemical Society.
