The Alexander Fleming Story of Discovering Penicillin Doesn't Hold Up

We've all heard the story of how Alexander Fleming discovered penicillin in 1928. He went on vacation and left an open petri dish of Staphylococcus bacteria sitting out. When he returned, the dish had the mold Penicillium rubrum growing in it, and the Staphylococcus nearest it were dead. The substance produced by the mold was named penicillin, hailed as a breakthrough in killing dangerous bacteria. 

But there were some problems with Fleming's story. First, no other bacteriologist could replicate the original petri dish that Fleming has discovered (Plate 1, which is still preserved almost 100 years later). Instead they discovered that Penicillium would not grow on a colony of Staphylococcus, and even if it did, it would only kill young, developing bacteria. There was the curious fact that Fleming didn't take notes on his observation for almost two months, and only included the discovery story in a write up of experiments with Penicillium. And some of the details of the story were only added years later, when Fleming admitted he might not recall it all correctly.  

So what happened in Fleming's lab to result in Plate 1? There have been lots of theories, a couple of them quite plausible. Bacteriologist Ronald Hare actually replicated Plate 1 after many attempts, but only by making some assumptions and changing the conditions to fit the results. His sequence of events relies on some amazing coincidences, and doesn't really explain Fleming's actions afterward. Professor Robert Root-Bernstein has another theory that credits Fleming's work but infers he added the intriguing story of the initial discovery afterward. Read up on the question of penicillin and how it may have been discovered at Asimov Press. -via Damn Interesting