Six petrie dishes growing penicillin, taken by James Jarche for Illustrated magazine in 1943. A strain of penicillin mould grows on the surface of each culture dish. The samples were grown by Alexander Fleming himself. From top left to bottom right the photograph shows the rate of growth from one to ten days. 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. 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.
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