How did Alexander Fleming discover penicillin?

Answer:
Alexander Fleming's discovery of penicillin came about by accident.

Fleming was an untidy worker, often leaving his equipment uncleaned. When he went away for a holiday during 1828, he left a clutter of plates growing various bacteria lying about his desk. After he returned, whilst working on an influenza virus he noticed that mould had grown on a staphylococcus culture plate. Not only that, the mould had created a bacteria-free circle around itself. Working on an hypothesis, he experimented further to determine that even a weaker-strength mould culture prevented growth of staphylococci. Thus, Fleming initiated the development and practice of antibiotic therapy for infectious diseases.
First answer by Maxyahr1. Last edit by On the Wallaby. Contributor trust: 2764 [recommend contributor recommended]. Question popularity: 1 [recommend question].