4. Penicillin
In 1928, Dr. Alexander Fleming returned from a vacation to find that a mold had contaminated a petri dish containing colonies of Staphylococcus bacteria in his laboratory at St. Mary’s Hospital in London. Upon closer examination, he observed that the bacteria surrounding the mold were destroyed, while those farther away remained unaffected. Recognizing the potential significance of this observation, Fleming identified the mold as belonging to the genus Penicillium. He named the antibacterial substance it produced “penicillin.” This serendipitous discovery marked the beginning of the antibiotic era, revolutionizing medicine and saving countless lives (sciencehistory.org).
