Alexander Fleming

Alexander Fleming was a Scottish bacteriologist, born near Darvel in 1881 and died in London in 1955. Returning to his cluttered laboratory at St Mary's Hospital in London from a holiday in September 1928, he noticed that a mould, later identified as Penicillium notatum, had contaminated a culture plate of Staphylococcus bacteria he had left out, and that the bacteria near the mould had been killed. He identified the active substance as penicillin and published his findings in 1929, but could not purify or produce it in useful quantity himself; that work fell to Howard Florey and Ernst Chain a decade later, and the three shared the 1945 Nobel Prize in Physiology or Medicine. The discovery is one of science's best-known accidents, and Fleming himself credited chance in his Nobel lecture, though it was his trained eye that recognised what the chance contamination meant rather than discarding the spoiled plate.