09/29/2026
An important day indeed 🔬
On this date in history, September 28, 1928, a bit of untidiness led to one of the most important discoveries in medicine.
𝗔𝗹𝗲𝘅𝗮𝗻𝗱𝗲𝗿 𝗙𝗹𝗲𝗺𝗶𝗻𝗴 returned to his laboratory at St. Mary’s Hospital, London, after a holiday and noticed an unusual mould growing on a culture plate of 𝗦𝘁𝗮𝗽𝗵𝘆𝗹𝗼𝗰𝗼𝗰𝗰𝘂𝘀. Around the mould was a clear zone where the bacteria had failed to grow, suggesting that the mould was producing an antibacterial substance.
Fleming identified the mould as belonging to the genus 𝗣𝗲𝗻𝗶𝗰𝗶𝗹𝗹𝗶𝘂𝗺 and initially referred to the antibacterial substance as “mould juice.” He later named it penicillin. His findings were published in 1929, demonstrating its ability to inhibit the growth of several bacteria.
Although Fleming’s discovery was groundbreaking, penicillin was difficult to extract, purify, and produce in sufficient quantities. More than a decade later, Howard Florey, Ernst Chain, and their colleagues developed methods for producing and purifying penicillin on a larger scale, enabling its clinical use, particularly during World War II.
Penicillin primarily acts by inhibiting bacterial cell-wall synthesis, preventing susceptible bacteria from maintaining cell-wall integrity. In 1945, Fleming, Florey, and Chain were awarded the Nobel Prize in Physiology or Medicine for the discovery of penicillin and its curative effect in infectious diseases.
