High Quality Content by WIKIPEDIA articles! Sir Alexander Fleming, FRSE, FRS, FRCS(Eng) (6 August 1881 – 11 March 1955) was a Scottish biologist, pharmacologist and botanist. He wrote many articles on bacteriology, immunology, and chemotherapy. His best-known discoveries are the enzyme lysozyme in 1923 and the antibiotic substance penicillin from the mould Penicillium notatum in 1928, for which he shared the Nobel Prize in Physiology or Medicine in 1945 with Howard Florey and Ernst Boris Chain.