Discovery of Penicillin

On September 28, 1928, Alexander Fleming returned to his lab at St. Mary's Hospital to find that a mold (Penicillium notatum) had contaminated a petri dish and killed the surrounding staphylococcus bacteria.

This serendipitous discovery led to the development of penicillin, the world's first antibiotic, saving millions of lives and revolutionizing the treatment of infectious diseases.