Penicillin
Scottish biologist Sir Alexander Fleming changed the course of the twentieth century when he discovered the penicillin family of life-saving antibiotics.
Although he noticed that the mould inhibited bacterial growth and managed to culture it, it wasn’t until Australian pharmacologist Howard Walter Florey stabilised the compound that it began to save patients. Florey, Fleming and Anglo-German biochemist Sir Ernst Chain were awarded the Nobel Prize in Physiology or Medicine for their work.