Alexander Fleming

Alexander Fleming was a Scottish physician and bacteriologist working at St Mary's Hospital in London. He studied infections and substances that inhibit bacterial growth. In 1928 he noticed a mould on one of his culture plates, around which staphylococcus colonies were not growing. Instead of discarding the contaminated dish, he treated the zone of inhibition as an experimental question.

Fleming cultured the mould and investigated the filtrate, testing its action against various bacteria. In a paper of 1929 he described the antibacterial action of Penicillium cultures and named the active substance penicillin. The result was important, but the preparation proved difficult to purify and unstable. Fleming's laboratory did not yet produce a medicine suitable for safe, large-scale treatment of patients.

The next stage belonged to the teams that developed purification, dosage and production. Howard Florey, Ernst Boris Chain and their colleagues carried out the work that turned an observation into a therapy, and industry scaled it up during the Second World War. The Nobel Prize in 1945 was shared by Fleming, Chain and Florey. That division of credit matters: discovering the phenomenon, explaining the substance and creating the medicine were different tasks.

For MykoRadar, Fleming's story shows that the significance of fungi does not end with fruiting bodies. A mould produces a compound that acts on competing microorganisms, and people learned to isolate and apply it. Penicillin does not act on all bacteria, and misuse of antibiotics selects for resistance. The legacy of the discovery is therefore not a promise of a universal medicine, but a method: careful observation, controlled experiment and long collaboration between laboratory, clinic and production.

It is also worth separating the mould from the finished preparation. Species, strain, culture conditions and the method of purification all affect the yield of the substance. Eating or home-culturing a random fungus is not treatment. An antibiotic works because of a controlled dose, quality, and correct diagnosis of the infection.

Discovery, laboratory test and medicine are three stages

Fleming’s 1929 paper was titled “On the Antibacterial Action of Cultures of a Penicillium, with Special Reference to Their Use in the Isolation of B. influenzae.” The final clause matters: in the paper penicillin was also a selective laboratory tool that inhibited some bacteria and helped isolate others, not a mass-produced finished medicine. In his Nobel lecture Fleming reconstructed the clearing of staphylococcal colonies around the contaminating mould, its isolation and the testing of culture filtrate. Yet the 1945 prize was shared by Fleming, Ernst Chain and Howard Florey “for the discovery of penicillin and its curative effect in various infectious diseases.” That wording prevents a one-moment, one-person myth. Observation, characterisation, purification, experimental treatment and clinical deployment were distinct but interdependent pieces of work. The mould plate begins the story; it does not contain the whole therapeutic programme.