Penicillin antibiotic used successfully to treat serious human diseases. British scientist Alexander Flemming discovered the drug in 1928. He observed at mold growing in a laboratory dish containing bacteria had killed the bacteria surrounding the mold He then experimented with the mold. He grew it in a liquid broth to determine if bacteria would grow in test tubes containing the broth. They did not. Fleming, however failed to find a way of the bacteria-killing This did and Ernst Chain, the late 1930 when a researchers, led by Howard developed a method for purityingsmall amounts of an antibacterial drug from Fleming's mold, which came from the genus Penicillium.