Sir Alexander Fleming Scientist 1881-1955

Sir Alexander Fleming won the Nobel Prize for his discovery of Penicillin - as well as the antibiotic substance lysozyme - which have both been used to save millions of lives since.

He was born on a farm in Lochfield, in East Ayrshire, in 1881. He was educated in nearby Kilmarnock, before attending St Mary's Hospital Medical School in London. When World War I broke out, he - and many of his colleagues - treated the casualties on the frontline. The incapacity to treat the men properly drove him to develop an much better antiseptic on his return to Britain at the end of the War.

Scientists are usually known for their cleanliness and care. It was actually because Fleming was disorganised that his two major discoveries were made.

He discovered Lysozyme after sneezing into a Petri dish filled with bacteria. A few days later, he discovered that the bacteria in the areas he had sneezed had been killed off. He deduced that the body created its own enzyme to fight off dangerous bacteria.

His most famous discovery - Penicillin - was the result of him running numerous experiments around the lab, without much care as to where they ended up. It was Fleming was cleaning some of them out that he noticed a Fungal Colony had grown next to a streak of bacteria on a sheet of glass. The bacteria around the fungus had died, as the cells were breaking down (known as lysis). Although he knew this was significant, he didn't realise that it would become one the greatest discoveries of the century.

He played with growing the mould for some time, but eventually gave up - feeling that it would be too difficult to manufacture on a scale that would be useful. He passed the process over Howard Florey and Ernst Boris Chain, who perfected the process of purification - and were able to make it available in time for World War II. It is believed to have saved millions of lives during the six-year period.

For their work, Fleming, Florey and Chain jointly received the Nobel Prize for Medicine in 1945. Fleming had been knighted a year earlier.