In 1928, Scottish Scientist Sir Alexander Fleming was studying Staphylococcus – the bacteria that causes food poisoning. He turned up at work one day and discovered a blue-green mould that seemed to be inhibiting growth of the bacteria. He grew a pure culture of the mould and discovered that it was a Penicillium mould. After further experiments, Fleming was convinced that penicillin could not last long enough in the human body to kill pathogenic bacteria, and stopped studying it after 1931, but restarted some clinical trials in 1934 and continued to try to get someone to purify it until 1940. The development of penicillin for use as a medicine is attributed to the Australian Nobel Laureate Howard Walter Florey – he shared the Nobel Prize with Fleming and Ernst Boris Chain.