It was on this day in 1928 that Scottish bacteriologist Alexander Fleming peered into a petri dish at his basement laboratory in London and noticed a blue-green mold growing. The mold, he observed, was killing the staph bacteria he'd been cultivating in that petri dish. He called the mold "penicillin." Penicillin is now considered the world's first "miracle drug," and it sparked the modern era of antibiotic development.
Fleming's discovery of penicillin has often been called ... serendipitous. He'd left the petri dish out by accident instead of putting it away in the incubator, and then he'd gone off on holiday for a couple of weeks. The damp, chilly London air had given the mold the right conditions to grown in.
But, as scientist Pasteur said, fortune favors the prepared mind. When Fleming looked into the dish and saw that blue-green mold and the growth pattern of the bacteria, he deduced that the moldy bit must be the thing that was preventing the bacteria from spreading. Noticing that penicillin was an antibacterial agent was a big deal, but it was still many steps away from making penicillin the world's most effective antibiotic. To do this, scientists needed to find a way to purify the mold - and then a way to mass-produce it.
It took a team of Oxford scientists, a Rockefeller Foundation grant, and more than a decade of experimenting to make the strain of penicillin that would become the amazingly effective infection-fighting, lifesaving antibiotic that it is today. The task became extra urgent with the start of World War II. Soldiers would survive a wound in battle only to be killed by a nasty infection from that wound later. Penicillin could cure these infections.
The team of scientists working on purifying penicillin moved their lab out of England, for fear that it would be bombed, and over to the U.S. There they experimented with the best way to grow large amounts of penicillin. They used big vats for fermenting the mold. They found that the mold from a moldy cantaloupe was the best kind of mold to start with. And they found that dumping in a by-product from corn production called corn steep liquor really helped - it made their penicillin broth about 15 times more productive. They shot UV rays and X-rays at their molds, hoping to make more productive strains. They knew they had finally succeeded when they gave lab mice lethal doses of bacteria, and then used penicillin to save the lives of those mice. candy or blushing pink wears for flower girls
Penicillin works to kill bacteria because it prevents bacteria from correctly forming new cell walls. Without the new cell walls, the cells cannot divide properly, and so they cannot reproduce, and so the bacteria die off.
Fleming and the scientists who purified penicillin won the 1945 Nobel Prize in medicine. There are several versions of penicillin now, and they are still prescribed to treat a variety of infections. It's the most widely used antibiotic in history.