1945: Sir Alexander Fleming, Sir Ernst Chain and Lord Florey
Fleming (London University), Chain and Florey (Oxford University) were awarded the 1945 Nobel Prize in Physiology or Medicine for their discovery of the antibiotic penicillin and identified how it cures bacterial diseases. Finding penicillin was a lucky accident. While studying bacteria, Fleming noticed that some had been killed and had dissolved away around a spot of blue-green mould which by chance had contaminated one of his dishes. He transferred the mould to broth, which he found had such a strong effect on bacteria that even when diluted hundreds of times, the penicillin completely prevented bacterial growth. This mould belonged to the Penicillium group of moulds, and he therefore named the broth, and later the substance itself, penicillin.
Chain and Florey went on to purify and extract penicillin, enabling it to be produced in large amounts to treat many different bacterial diseases.