Penicillium Mould from Profesor Alexander Fleming, 1935.
© Science Museum / Science & Society Picture Library
Mounted petri dish containing Pencillin culture, originally belonging to Alexander Fleming (1881-1955). This sample marks penicillin's transition from an interesting phenomenon to a potential drug. In 1928 Alexander Fleming (1881-1955) had discovered that a strain of penicillium mould exuded a substance which killed certain bacteria. Following the German firm IG Farben's announcement of the first general purpose bacteria-killing drug Prontosil, Fleming now saw it as a posible medicine and gave this sample to a colleague at St Mary's Hospital, London. Penicillin was eventually isolated in 1939, and from 1942 became an important drug.