Test tubes of penicillin, 1943.
© NMeM / Daily Herald Archive / Science & Society Picture Library
Penicillin growing in test tubes, taken by James Jarche for Illustrated magazine in 1943. Penicillin is an antibiotic, a chemical effective at very low concentrations which can kill or stop the growth of a disease-causing microbe. Penicillin is produced naturally in moulds of the genus Penicillium, from where the drug gets its name. Alexander Fleming identified the antibacterial properties of the penicillium mould in 1928. The Oxford team of the Australian Howard Florey (1898-1968) and German-born British biochemist Ernst Chain (1906-1979) isolated penicillin and developed it as an antibiotic just before and during WWII.