A laboratory no one envied
London, summer 1928. On the third floor of St Mary's Hospital, in the Paddington district, a small cluttered laboratory defies all the rules of scientific hygiene. Petri dishes pile up on the benches, some open, others forgotten for weeks. Test tubes lie among the stacks of handwritten notes. A cigarette butt smoulders in an ashtray, a few centimetres from living bacterial cultures. The man who works here is called Alexander Fleming. He is 47, a professor of bacteriology, and his laboratory is, by the admission of all his colleagues, a shambles.
V.D. Allison, his research assistant, would later say with a touch of affectionate irony: "If Fleming had been as tidy as he thought I was, he would never have made his two great discoveries." For this disorder was not a mere character flaw. It was, without Fleming fully realising it, a method. Or rather, an absence of method that would prove more fruitful than all the procedures in the world.
The man behind the disorder
To understand the discovery of penicillin, you first have to understand Fleming. Born in 1881 on an isolated farm in Lochfield, Scotland, Alexander grew up on the moors, observing nature with insatiable curiosity. After studying medicine at the Polytechnic School in London, he joined in 1906 the laboratory of Almroth Wright at St Mary's Hospital, a place that would become his second home for nearly fifty years.
Fleming had a character trait rare among scientists of his time: he did not throw away his failed experiments. Where his colleagues methodically cleaned their cultures after each observation, he kept them. He let the Petri dishes accumulate on his bench, sometimes up to forty or fifty at a time, for two to three weeks. He smoked above his cultures. He opened the lids without precaution, exposing his samples to the ambient air of the laboratory. It was not laziness. It was a form of intuition: Fleming knew, confusedly, that something interesting might arise in these abandoned cultures. He liked to say he played with his microbes as a child plays with his toys.
As early as 1922, this habit had already brought him luck. Suffering from a cold, Fleming had let a drop of nasal mucus fall onto a Petri dish containing bacteria. Anyone else would have cleaned up and started again. Not Fleming. He set the dish aside and waited. A few days later, he found that the bacteria had been destroyed around the drop. He had just discovered lysozyme, a natural antibacterial enzyme present in tears, saliva and mucus. A minor discovery in appearance, but one that already revealed the Fleming method: let things happen, observe, then understand. A precedent that would change everything six years later.
The holiday departure that changed history
In late July 1928, Fleming prepares his summer family holiday at his country house in Suffolk. Before leaving, he inoculates several Petri dishes with colonies of Staphylococcus aureus, the bacterium responsible for many hospital infections. He pushes the dishes into a corner of his bench to free up space for his colleague Stuart Craddock, who is to work in his absence.
And then Fleming makes two mistakes. First, he does not place all his cultures in the disinfectant bath as the protocol requires. He simply piles a few dishes on a tray, in plain view, without a protective lid. Second, he leaves the laboratory windows ajar, probably to air the room in this period of summer heat. Two lapses that, in any modern quality audit, would earn a reprimand, even a suspension. But it is precisely this double negligence that will open the door to one of the greatest medical discoveries of all time.
During his absence, London experiences a particularly capricious summer. Temperatures fluctuate unusually: first cool, below 20°C, favouring the growth of moulds, then warmer, around 25°C, ideal for bacteria. This unique climatic sequence creates the perfect conditions for a phenomenon no one could have planned. A spore of Penicillium notatum, carried by the wind through the open window, lands on one of the Petri dishes neglected by Fleming.
"That's funny": two words that saved the world
On 3 September 1928, Fleming returns from holiday. He finds his laboratory in the state he left it: cluttered, untidy, scattered with forgotten cultures. He begins to sort his Petri dishes, plunging them one by one into the disinfectant tank. It is then that a former colleague, D. Merlin Pryce, drops by. Fleming, dish in hand, stops dead.
On one of the staphylococcus cultures, a blue-green patch of mould has developed. So far, nothing extraordinary: mould contaminations are commonplace in laboratories. But Fleming observes something else. All around the mould, within a radius of several centimetres, the bacterial colonies have disappeared. The agar, the gelatinous culture medium, has become transparent, as if the bacteria had been dissolved.
Fleming then utters two words that became famous in the history of science: "That's funny." Not "Eureka". Not "I have found it." Just "That's funny." A modest, almost casual reaction, but one that reveals an essential quality in the innovator: the ability to notice the anomaly. Where any other bacteriologist would have thrown away the contaminated dish without a glance, Fleming stops, observes and wonders. This capacity for astonishment, this deliberate slowness in the face of the unexpected, is perhaps Fleming's true genius. He was not looking for penicillin. He was not looking for anything specific. But he was ready to welcome what chance brought him.
Intuition at work
What sets Fleming apart is not the stroke of luck. It is what he does with that stroke of luck. Instead of getting rid of the contaminated culture, he sets it aside, photographs it, shows it to his colleagues. He isolates the mould and identifies it as belonging to the genus Penicillium (it would later be reclassified as Penicillium rubens). He grows this mould separately and tests the liquid it produces, which he names "penicillin", on other bacterial strains.
The results are astonishing. The "mould juice", as he familiarly calls it, kills staphylococci, streptococci, pneumococci and the diphtheria bacillus. Fleming also discovers that this substance is not toxic to human white blood cells, a crucial property that distinguishes it from the chemical antiseptics of the time, which destroyed the patient's cells as readily as the bacteria.
In 1929, Fleming publishes his results in the British Journal of Experimental Pathology. The article is rigorous, factual, almost discreet. But the scientific community barely reacts. The problem is twofold. On one hand, Fleming is not a chemist: he cannot isolate and purify penicillin in sufficient quantity for clinical trials. On the other, antibiotics do not yet exist as a concept. No one is looking for that kind of molecule, so no one understands the scope of the discovery.
Fleming, lucid about his own limits, does not give up entirely but moves on to other subjects. For more than ten years, penicillin remains a laboratory curiosity, a footnote in bacteriology journals.
The revival: Florey, Chain and the Second World War
It would take until 1940 for two researchers at the University of Oxford, Howard Florey and Ernst Boris Chain, to pick up the thread of Fleming's discovery. Chain, a German biochemist of Jewish origin who had fled to England to escape Nazism, comes across Fleming's 1929 article while leafing through old bacteriology journals. Intrigued by this "mould juice" no one had managed to exploit, he convinces Florey, a pragmatic and determined Australian pharmacologist, to take an interest in it. Together, with a team of biologists and chemists, they finally manage to isolate, purify and concentrate penicillin. In May 1940, when Europe is already at war, they conduct a decisive trial on eight mice infected with deadly streptococci: the four that receive penicillin survive, the other four die in the night.
The entry into war accelerates everything. In February 1941, the first human patient, Albert Alexander, a London policeman suffering from septicaemia after scratching his face on a rose bush, receives injections of penicillin. His condition improves spectacularly within days. But the supplies run out before full recovery, and Alexander eventually succumbs to the infection. This tragic half-failure nevertheless proves the extraordinary effectiveness of the molecule. The problem is no longer scientific: it is industrial. How to produce this substance in sufficient quantities?
It is the American pharmaceutical industry, mobilised by the war effort, that will find the answer. Thanks to deep fermentation techniques and the discovery of a particularly productive Penicillium strain on a mouldy melon found in a market in Peoria, Illinois, production explodes. In June 1944, during the Normandy landings, the Allied forces have 2.3 million doses of penicillin to treat the wounded in the field. The antibiotic will save an incalculable number of lives among soldiers and civilians.
In 1945, Fleming, Florey and Chain jointly receive the Nobel Prize in physiology or medicine. In his speech in Stockholm, Fleming already warns of the danger of bacterial resistance: if penicillin is used at doses too low or for durations too short, bacteria could learn to resist it. "It is not difficult to make microbes resistant to penicillin in the laboratory", he declares, "and the same thing can happen in the body." A prophetic warning that the world would take decades to take seriously, and whose consequences catch up with us today in the global crisis of antibiotic resistance.
The lessons for innovation
The story of penicillin is often told as a scientific fairy tale: an absent-minded researcher, a gust of wind, a providential mould. But that reading is misleading. Fleming's discovery is not the fruit of pure chance. It is the product of a rare convergence between negligence, preparation and intuition.
First lesson: disorder can be a space for discovery. Fleming did not leave his laboratory untidy out of laziness, but out of a kind of experimental instinct. By letting his cultures lie around, he involuntarily created the conditions for an observation that strict protocols would have made impossible. In the world of innovation, this means that overly rigid processes can kill serendipity. Companies that standardise every step of their R&D gain in efficiency, but lose in capacity for surprise.
Second lesson: observation counts more than experiment. Fleming did not discover penicillin because he was looking for it. He discovered it because he knew how to see what others would not have noticed. Fleming's "That's funny" is a reflex every innovator should cultivate: faced with an unexpected result, do not correct the anomaly, but explore it.
Third lesson: a discovery is nothing without the means to realise it. Fleming identified the potential of penicillin, but it took Florey, Chain and the American industry to turn it into a drug. Innovation is never a solitary act. It requires an ecosystem: a mind that observes, minds that develop, and structures that produce.
Louis Pasteur was right: "Chance favours only the prepared mind." Fleming's untidy laboratory was not an accident. It was the fertile ground of a mind that knew how to stay open to the unforeseen. Today, the most innovative companies know it: Google historically devoted 20% of its engineers' time to personal projects, 3M encouraged its researchers to explore off-programme paths. These are modern versions of Fleming's laboratory, spaces where controlled disorder is not only tolerated but encouraged.
And this is perhaps the most important lesson for all those who seek to innovate: do not tidy away too quickly what does not look like what you expected. Keep a corner of the bench for the unforeseen. Let your ideas lie around, even the most shaky ones. For it may be there, in what you were about to throw away, that the next revolution is hiding.