University years

How did Fleming discover penicillin?

After that first “basic” first year we finally got into the real biology world and it didn’t start easy at all: the first semester of my second year in Biotechnology was basically the two courses of Biochemistry and Molecular Biology, the two beasts of every degree that has something related to biology (and this includes also Medicine, Nursing, Chemical and Pharmaceutical Technologies and so on).

If in my previous post I said that the toughest thing of the university was getting adjusted to live by myself, this first semester of the second year involved studying like there was no tomorrow to understand and remember the metabolic pathways of the cell (and how these are integrated first among cells and then among tissues), but also how our genetic code is replicated and translated into proteins, how these proteins are actually build up and how all this knowledge can be used in research and in industries. All these courses are the biological basis to understand how life is working (so far as we currently know it) to then proceed to apply all this knowledge to more specific topics and lectures, that started the second semester of this pretty busy second year.

Anyway, I will write about the second semester of my Biotechnology bachelor in the next posts, but today I would like to talk a bit about a very interesting course that I had to attend that first semester that was called “General and Medical Microbiology”. It started with a pretty cool introduction to the history of microbiology and it rapidly moved on to how we are taking advantage of bacteria and other microorganisms to ferment things (beer as an example, but also yogurt, bread, and so on) and to produce molecules used in medicine (an example could be the production of insulin, used by people with diabetes, but also the production of antibiotics). The second part of this course focused more on the medical side of the microbiological world, talking about the diagnostic of infectious diseases and the role of the microorganisms in the human pathology. I have never considered myself as a hypochondriac person, somebody that gets easily scared by diseases and infections, but as soon as I had the chance, I went to the hospital to get checked for many of the bacteria and viruses I studied and I got my vaccinations up to date.

Since vaccines are a really hot topic right now and since I believe people need to be more aware of the importance of immunisation through vaccines, I will write soon a whole post on this topic (from the history of vaccines to what they actually does to our bodies and why it is important we get immunised). For today, for the SRF, I want to talk about the discovery of the penicillin and how this discovery shows that luck goes hand in hand with knowledge.

“Science Related Fact” (SRF):

I am going to start the this SRF with a pretty bold statement that caused me an argument with a professor during a PhD interview: the discovery of penicillin was fortuitous. Until the first years of the 20th century there was no effective treatment for infections such as pneumonia or gonorrhoea and hospitals were full of patients with blood poisoning contracted from a cut or a scratch and full of doctors that could do little for them but wait and hope. Research in this field was languishing as well, up until the 3rd of September 1928, when Alexander Fleming, Professor of Bacteriology at St. Mary’s Hospital in London, came back from holidays and began to sort out petri dishes containing colonies of Staphylococcus. He noticed that one of these dishes was dotted with colonies, except for one area where some mould was growing. The zone around the mould was clear as if the mould had secreted something that inhibited bacterial growth. Fleming found that this particular mould was capable of killing a wide range of harmful bacteria (see picture below).

“Penicillin resistance in bacteria”. Petri dish cultures of bacteria, where bacterial growth appears opaque and grey on the surface of the growth medium.  A white pellet of penicillin drug is seen at the top of the dish. The bacteria show sensitivity to the penicillin drug by forming a clear zone of inhibited growth around the pellet. Modified from Pearson Education Inc., on

It was such a lucky discovery, but, as I mentioned above, “luck goes hand in hand with knowledge”: there could have been another kind of bacteria growing on that petri dish; the fungus that was growing on that dish is a rare strain of Penicillium notatum, so it could have just simply been another strain of fungi not producing penicillin; Fleming could have just ignored the weird mould growing on the dish and threw it in the trash, without trying to figure out what was happening in that culture.

When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionise all medicine by discovering the world’s first antibiotic, or bacteria killer. But I guess that was exactly what I did“, Fleming later wrote about his discovery.

Its incredibly huge discovery was not fully understood and appreciated in those years, due to the difficulties in isolating the penicillin. However, its life saving potential and in particular the efforts of isolating the molecule increased and saved many lives during WWII. In 1945, he was awarded the Nobel Prize in Medicine along with Florey and Chain, his collaborators.

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