Thesis: The Discovery of Penicillin

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Thesis: The Discovery of Penicillin

This sample thesis writing discusses the Discovery of Penicillin and its development. Alexander Fleming discovered Penicillin by accident in 1928.

Actually, he was looking for a way to destroy bacteria by cultivating bacteria on agar plates. He was not a very tidy and sometimes did not cover his agar plates appropriately which exposed the plates to the outside environmental air.

Alexander was going on holiday in 1928 and being a careless person he made two mistakes that led to the accidental discovery of the wonder drug. The first mistake was that he did not sterilize all the plates with bleach and secondly he did not close his windows which brought in the outside air in abundance.

The Discovery of Penicillin

The age of antibiotics began with the discovery of penicillin. Before its invention, there was no cure for illnesses like gonorrhea, rheumatic fever, or pneumonia. The only thing doctors could do for the many hospital patients who had blood poisoning from cuts or scratches was to wait and hope.

Antibiotics are substances produced by bacteria and fungi that may either kill or suppress rival microbial species. This phenomenon has long been recognized, and it may be the reason why the ancient Egyptians used to treat infected wounds with a moldy bread poultice.

Yet, it wasn’t until 1928 that Alexander Fleming, a professor of bacteriology at St. Mary’s Hospital in London, made the discovery of penicillin, the first real antibiotic.

Alexander Fleming’s Discovery of Penicillin – September 3, 1928

Upon returning to his lab after his holidays, he discovered that several of his culture plates were covered with a common mold that grew because a slice of bread had landed on Alexander Fleming’s plate. This lucky omission resulted in the discovery of Penicillin which has saved millions of lives since its invention.

While washing the plates, Fleming noticed that although a lot of bacteria had grown in his places, there was a ring in the jelly around some of the mold spots where no bacteria were in evidence. Something had destroyed the bacterium that was covering the jelly.

Fleming realized the importance of this occurrence, and he exerted a lot of effort in squeezing the ‘mold fluid’ and called it penicillin. However, the problem was that he could not extract much penicillin from the mold and it could not be preserved even when refrigerated.

He had no way of proving that this mold could actually destroy bacteria. Because of these difficulties, Fleming stopped working on the penicillin mold and concentrated his energies on other projects.

Mold Juice

Streptococcus, meningococcus, and the diphtheria bacillus were just a few of the deadly germs that Fleming discovered his “mold juice” was capable of eliminating.

He subsequently gave the challenging task of extracting pure penicillin from the mold juice to his subordinates Stuart Craddock and Frederick Ridley. They could only make rudimentary material solutions since they turned out to be exceedingly unstable.

Only a cursory mention of penicillin’s possible therapeutic advantages appeared in Fleming’s findings, which were published in the British Journal of Experimental Pathology in June 1929.

The separation of penicillin-sensitive bacteria from penicillin-insensitive bacteria in a mixed culture appeared to be its primary use at this point. This at least provided bacteriologists with a useful benefit and maintained an interest in penicillin.

Attempts to purify penicillin were made by others, including Harold Raistrick, Professor of Biochemistry at the London School of Hygiene and Tropical Medicine, but they were unsuccessful.


Later in 1938, Howard Florey and Ernst Chain who were at Oxford University decided that they should try and make some use of penicillin. They started their experiments on mice and injected eight mice with some bacteria to kill them. Then four of the mice were given penicillin.

They stayed healthy while the four mice without penicillin died. This gave them the confidence to treat a 43 old policeman, Albert Alexander who was dying because of a blood infection.

When treated with penicillin he started getting better until they ran out of penicillin. Without the penicillin, Albert died but his short period of recovery had provided great encouragement for Chain and Florey who collected more penicillin and treated a 15-year-old boy who had an infection after an operation. The boy completely recovered and the value of penicillin was confirmed.

Penicillin Research at Oxford University

Penicillin was a laboratory oddity that Howard Florey, Ernst Chain, and their colleagues at Oxford University’s Sir William Dunn School of Pathology transformed into a life-saving medication.

They started working on the chemistry and purification of penicillin in earnest in 1939, just as the start of World War II made research increasingly challenging. The team needed to filter up to 500 liters of mold filtrate every week in order to carry out a program of animal studies and clinical trials.

They started cultivating it in an odd assortment of culture containers, including bathtubs, bedpans, milk churns, and food tins. Eventually, a specialized fermentation tank was created to make it simple to remove the mold and to conserve space by replenishing the broth under the mold’s surface.

At £2 a week, a group of “penicillin girls” were hired to inoculate and manage the fermentation in general. In essence, a penicillin factory was being created in the Oxford laboratory.

Meanwhile, using a countercurrent technique, scientist Norman Heatley recovered penicillin from massive amounts of filtrate leaving the manufacturing line by extracting it into amyl acetate and then back into the water.

Prior to clinical trials, Edward Abraham, a different scientist hired to assist in increasing production, utilized the recently developed method of alumina column chromatography to remove impurities from penicillin.

Florey conducted crucial research in 1940 that demonstrated penicillin could save mice from infection with lethal streptococci. The first person to receive Oxford penicillin was a 43-year-old policeman named Albert Alexander on February 12, 1941.

He had scraped the inside of his mouth while trimming rosebushes, which led to a serious infection that had spread to his eyes, face, and lungs. After receiving an injection of penicillin, he quickly made a remarkable recovery.

He passed just a few days later when the drug’s supplies ran out. However, some patients saw better outcomes, and soon there were preparations to provide penicillin to British soldiers on the front lines.

Production in the United States during WWII

For the long clinical studies necessary to verify the promise of the preliminary findings and to provide sufficient supplies of the medication for therapeutic usage in the event that it did live up to its potential, significant volumes of penicillin would be needed.

Given that the chemical industry in Britain was completely consumed by the war effort, Florey realized that large-scale penicillin manufacture was definitely out of the question.

In order to see whether they could persuade the American pharmaceutical industry to join the endeavor to make penicillin on a wide scale, Florey and his colleague Norman Heatley flew to the United States in the summer of 1941 with the assistance of the Rockefeller Foundation.

John Fulton, a physiologist at Yale, assisted his British colleagues by connecting them with potential resources. They were recommended to the Department of Agriculture’s Robert Thom, a renowned mycologist, and expert on the Penicillium mold, and then, due to the facility’s Fermentation Division’s knowledge, to the Northern Regional Research Laboratory (NRRL) in Peoria, Illinois.

This relationship turned out to be essential to the project’s success since the NRRL was a major source of the breakthroughs that made penicillin manufacturing on a big scale feasible.


One of the most important moments in the history of medicine was the discovery of penicillin. It transformed the way bacterial infections are treated and helped save countless lives.

Alexander Fleming made the discovery of penicillin in 1928 after seeing that a mold called Penicillium notatum had infected one of his petri dishes and prevented the development of germs nearby.

The finding made by Fleming represented a major advance in the battle against bacterial diseases. It opened the door for the creation of antibiotics, which have since evolved into a fundamental component of contemporary medicine.

Due to penicillin’s widespread usage in World War II to treat injured troops, additional antibiotics that are still in use today were created as a result of penicillin’s success.

Antibiotic-resistant bacteria, however, have grown as a result of excessive antibiotic usage and now represent a serious threat to overall health. This emphasizes the significance of using antibiotics responsibly and the necessity of ongoing research and development of novel antibiotics.

Moreover, it should be noted that the discovery of penicillin marked a significant turning point in medical history and helped to save many lives. It continues to be an effective weapon in the struggle against bacterial diseases, and its discovery opened the door for the creation of further life-saving medicines.

To avoid the creation of germs that are resistant to antibiotics and to guarantee that these life-saving medications continue to work for future generations, it is crucial to use antibiotics wisely.