Penicillin was discovered by accident in 1928 by Alexander Fleming. The scientist conducted experiments with staphylococcus bacteria and, having forgotten the cup with them on the table, went on a business trip. Imagine his surprise when he returned home a few days later, when he saw through a microscope that bacteria multiplied everywhere, except for one place where mold had gathered. Yes, the same mold that can be seen on the ceiling, stale bread and many other places. Fleming realized that a substance in the mold was killing bacteria and isolated it, calling it penicillin. Further research has shown that penicillin inhibits the growth of harmful bacteria. Fleming revolutionized medicine by giving rise to antibiotics. For his discovery, he received the Nobel Prize in 1945.