In the mid 19th century, Louis Pasteur noticed that placing microscopic mushrooms near bacteria slowed down their growth. In 1927, Charles Latouche began studying different fungi and mold at St. Mary's Hospital. The airborne spores from the mushrooms were not well contained and traveled from the floor below to the lab of Alexander Fleming who was studying Staphylococcus Bacteria, which caused many illnesses. He noticed that the fungus that invaded his lab had almost destroyed the Staphylococcus colonies. The killer fungus was identified as Penicillium notatum, and it destroyed many different bacteria. In 1940, Ernst Chain and Howard Florey isolated and purified the active substance produced by the fungus: Penicillin. During WWII they used a melon with the right kind of mold to create enough penicillin to make medicine and commercialize it to treat soldiers and illnesses like pneumonia and meningitis. Penicillin kills bacterial growth, which makes it an antibiotic. Today the study of fingi comtinues.