Discovery of penicillin
Scottish-born bacteriologist Sir Alexander Fleming (1881-1955) discovered the antibiotic substance penicillin by accident.In 1928, after serving as an army doctor in World War I, Fleming was doing laboratory research at St. Mary's Hospital in Paddington.
One morning he noticed that a mold had developed overnight on a staphlococcus culture plate, and had created a bacteria-free circle around itself.
In further experiments, Fleming found the mold culture, which he named penicillin, would destroy bacteria without harming human cells. He published his results in 1929.
During World War II, new methods for mass-producing penicillin were developed, and the antibacterial agent saved many lives.