Alexander Fleming's Life Span Alexander Fleming discovered Penicillin. A drug which has the ability to fight of certain bacterias. He did this, completely by accident. He was experimenting in the creation of bacteria in petri dishes before he left for holiday with his family. Being a very messy man he didn't clean up his lab. When he returned, the bacteria had formed a ring of mould around it. After close observation, experimentation and recreation, he noticed the wonders this mould could perform, fighti (6 agos 1881 año