GenInv – Health and Wellness

Britain’s history is made up of very famous Scientists all through their history. This has made me decide to write about one of the most famous British Scientist – Sir Alexander Fleming the discoverer of Penicillin. The discovery of penicillin was more than a mere chance event.

 

Alexander Fleming’s discovery of penicillin is one of the most celebrated case of an accident in science. In the conventional story, a stray mould spore was borne through an open window and landed on an

exposed bacterial culture, Fleming later noticed a clear zone where the bacteria had been killed, he immediately recognized the therapeutic significance of the event, and it was only a matter of time before penicillin became a miracle drug. Fleming himself often underscored the role of chance in his work. Despite the numerous honours and awards he received, he was fond of reminding others, “I did not invent penicillin. Nature did that. I only discovered it by accident.”

There was even more

“chance” to the story than is often told, however. In addition, the traditional account obscures a considerable amount of scientific work that identified the efficacy of penicillin as an antibacterial agent. Without several researchers, who aggressively pursued the potential in Fleming’s initial observation, penicillin would probably not have become a “discovery” on this occasion. The fuller story suggests a more complex view of science–as guided both by the contingencies of circumstance a

nd by the focused effort of researchers.

Renewed interest in the history of Fleming’s work began quite a few years ago when a bacteriologist in London noted that the windows of Fleming’s lab at St. Mary’s Hospital were so constructed that they could not open. How could a stray mould spore have wandered in, even by chance? Second, he observed, spores of Penicillium will not germinate under the conditions described by Fleming. Someone else then observed that the particular species of Penicillium would not likely have been floating in the air of London. Though common bread mould is a variety of Penicillium, it was the much rarer P. notatum that produced Fleming’s penicillin.

The most likely source of the mould, it now appears, was a mycology lab downstairs from Fleming. There were likely spores all over the building. Further, Fleming was never known for neatness in his lab. Open cultures would not have been uncommon. It almost seems inevitable, then, that the mould would contaminate one of his cultures sooner or later.

The conditions of contamination would also have been important. Fleming believed, based on his earlier work on lysozyme, that penicillin acted by lysing bacteria open. This would certainly have accounted for the watery appearance of the area on his culture where the bacteria were absent. In this case, the spore would merely have needed to land on the culture plate–and this is how Fleming reported his own chance observation. But we have since learned that penicillin acts by blocking the synthesis of chemicals used by bacteria to build cell walls. Penicillin does not kill bacteria outright. Rather, it prevents their effective reproduction. A spore landing on an existing culture would thus be unlikely to have any immediate observable effect. The mould would have had to establish itself first if it was to prevent the further growth of bacteria. Temperature conditions while Fleming was away from his lab on vacation may have allowed this, or Fleming may have inoculated a plate that was already mouldy. In either case, a stray mould spore alone would not have created what Fleming observed.

The circumstance whereby Fleming noticed the original culture also seems quite improbable. Fleming did not notice the mould’s effect while routine-ly examining his cultures, though he did inspect them when he returned from his one-month summer vacation in 1928. In fact, he had discarded the now famous culture and left it to soak in a tray of lysol. A former member of his lab stopped by to visit, however, and Fleming showed him several cultures. Among these he casually selected the critical culture from the top of the discarded stack, where it had escaped the liquid disinfectant. Only then was Fleming struck by the unusual pattern of growth. He was obviously impressed, though, because he showed the culture to numerous colleagues the rest of the day and went on to investigate some of the strange antibacterial properties he saw.

Fleming was cer