Louis Pasteur’s Works – The Turning Point In The History Of Medicine


Louis Pasteur was born on Dec. 27, 1822, in Dole, France. Pasteur’s father was a tanner and the family was not wealthy, but they were determined to provide a good education for their son. At 9 years old, he was admitted to the local secondary school where he was known as an average student with a talent for art. When he was 16, Pasteur travelled to Paris to continue his education, but returned home after becoming very homesick. He entered the Royal College at Besançon where he earned a Bachelor of Arts. He stayed to study mathematics, but failed his final examinations. He moved to Dijon to finish his Bachelor of Science. In 1842, he applied to the Ecole Normale in Paris, but he failed the entrance exam. He reapplied and was admitted in the fall of 1844 where he became graduate assistant to Antoine Balard, a chemist and one of the discoverers of Bromine. Working with Balard, Louis became interested in the physical geometry of crystals. He began working with two acids. Tartaric acid and para tartaric acid had the same chemical composition, but appear different when the crystals were viewed under a microscope. How could chemically identical substances look different? Louis found that, when placed in solution, the two substances rotate polarized light differently. Louis Pasteur, one of the greatest benefactors of humanity, was the first person to see that bacteria causes diseases. He was a scientist who associated an animal disease with a microorganism. Pasteur solved the mysteries of rabies, anthrax, chicken cholera, and silkworm diseases. He also contributed to the development of the first vaccine. He described the basis of fermentation, wine-making using pasteurization and brewing of beer. Louis Pasteur’s life’s work can be divided into three main parts. Chemistry and the observation of crystals led him to study fermentation. And this led to his disproving of the spontaneous generation theory, a key discovery which opened the doors to microbiology and vaccination.

Pasteur’s work paved the way for many branches of science, making him responsible for some of the most important theoretical concepts of modern-day science. Before his discoveries, many had believed in the widely accepted myth of illness or disease due to spontaneous generation. However, he changed all that because of a key line of exploration; a French wine industry asked him to find out why some of their wine kept going bad. With the aid of a microscope, he saw microbes or tiny bacteria in the wine and realized that these might be causing its decay. He discovered that the germs died when he boiled the wine. The wine no longer went bad. It had been “pasteurized”.

Louis Pasteur - background and historical overview

At the time most doctors believed that germs were caused by 'spontaneous generation'. This meant that the germs grew out of wounds and not that they came to the wounds from the air itself. Pasteur carried out an experiment that proved this wrong. Pasteur had shown that germs causing decay are in the air all the time. His discovery was vital to the development of antiseptic surgery but he didn't stop there, he then isolated many bacteria that cause diseases. While in Strasbourg, Pasteur began studying fermentation. His work resulted in several improvements to the industries of brewing beer and making wine. In 1854, Louis accepted a position at the University of Lille, where he was asked by a local tradesman to help find out why some of the casks of fine vinegar made from beet juice were spoiling. Pasteur examined the good vinegar and the spoiled vinegar under the microscope. He knew that the yeast that caused the beet juice to ferment was a living organism. Casks producing good vinegar contained healthy yeast while those producing the spoiled product also contained microscopic rods that harmed the yeast. Pasteur hypothesized that these small “microbes” were also living organisms that could be killed by boiling the liquid. Unfortunately, this would also affect the taste of the vinegar. By careful experimentation, he discovered that the infecting microbes could be killed by controlled heating of the vinegar to 50-60 degrees Celsius (122-140 degrees F) and then rapidly cooling. Today the process is known as pasteurization.

Louis Pasteur - His great medical breakthrough and how it impacted the world

To most, Pasteur is remembered for his studies on pasteurization, a process named after him, but before he could demonstrate pasteurization, he needed an extra tool — the germ theory of diseases. For most of the medieval times, the prevalent theory regarding illnesses was the miasma theory. The miasma theory claims that diseases such as cholera, chlamydia and the plague were caused by a miasma — a noxious bad air. In the 1800s, people started questioning the theory, and some scientists (like John Snow) started writing essays about their observations regarding the invalidity of miasma theory. However, it was Pasteur that first proved that germs make us sick. He found not only that microorganisms can make us sick, but he also wrote recommendations on how to kill the germs and protect ourselves.


Pasteur demonstrated that fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is due not to spontaneous generation, but rather to biogenesis (Omne vivum ex vivo 'all life from life'). He was motivated to investigate the matter while working at Lille. In 1856 a local wine manufacturer, M. Bigot, the father of his student, sought for his advice on the problems of making beetroot alcohol and souring after long storage. In 1857 he developed his ideas stating that: 'I intend to establish that, just as there is an alcoholic ferment, the yeast of beer, which is found everywhere that sugar is decomposed into alcohol and carbonic acid, so also there is a particular ferment, a lactic yeast, always present when sugar becomes lactic acid.'

Principles of vaccination

In his research campaign against disease Pasteur first worked on expanding what was known about anthrax, but his attention was quickly drawn to fowl cholera. This investigation led to his discovery of how to make vaccines by attenuating, or weakening, the microbe involved. Pasteur usually “refreshed” the laboratory cultures he was studying—in this case, fowl cholera—every few days; that is, he returned them to virulence by reintroducing them into laboratory chickens with the resulting onslaught of disease and the birds’ death. Months into the experiments, Pasteur let cultures of fowl cholera stand idle while he went on vacation. When he returned and the same procedure was attempted, the chickens did not become diseased as before. Pasteur could easily have deduced that the culture was dead and could not be revived, but instead he was inspired to inoculate the experimental chickens with a virulent culture. Amazingly, the chickens survived and did not become diseased; they were protected by a microbe attenuated over time.


Using his work with fermentation, Pasteur was able to devise a process, now known as pasteurization, to kill microbes and preserve certain products. Pasteurization prevents fermenting and spoilage in beer, milk, and other goods.

Louis Pasteur helped save the silk industry

In the 19th century, silkworms in France were becoming infected with 2 diseases called pébrine and flacherie. This meant that farmers in southern France were being hit with big losses, and were therefore unable to produce large quantities of silk. Pasteur stepped in to try to save the day. He began to conduct experiments to try to figure out what was going on. He noticed that the infected silkworms were covered in something called a “corpuscle.” A corpuscle is simply a cell that is sometimes found in organisms. Pasteur concluded that the corpuscles were causing the pébrine disease in the silkworms. He went on to discover that the disease was heredity. He developed a technique to eradicate the disease: after the female silkworms laid their eggs, the eggs were then examined. If the eggs had corpuscles, they were quickly destroyed to stop the spread of pébrine. The silk farmers in France rejoiced!

The foundation of our knowledge about health and disease comes from the discoveries of this one man. He made many discoveries and solutions for problems of everyday life that are still in effect today. 


In 1868, Pasteur had a severe brain stroke which paralysed the entire left side of his body. He recovered, but in 1894, he suffered another stroke. This time he was unable to recover. He died in September of 1895 in Paris. At the time, he was given a state funeral and was then buried in the Notre-Dame Cathedral in Paris. His remains were eventually moved from the Notre-Dame and placed in a crypt in the Pasteur Institute in Paris. Since Louis Pasteur died his legacy didn’t end, in fact it grew there was institution built. Louis Pasteur’s life was filled with revolutionary discoveries and also marked by a number of events that likely fuelled his desire to understand the diseases of his time. A tireless and dedicated scientist, he travelled extensively throughout France to prove his theories and solve agricultural and industrial problems caused by infectious diseases. Pasteur founded an institute to carry on his legacy and continue his research. Today, the Institute Pasteur is one of the world’s leading research centres. It houses 100 research units and close to 2,700 people, including 500 permanent scientists and even more visiting scientists. Among the achievements of scientists working at the institute is a better understanding of diphtheria, a disease that used to kill thousands of children each year, a tuberculosis vaccine, a typhoid vaccine, and many other important achievements. These are just some of the events which Louis Pasteur, the brilliant scientist, is revered for today. His life wasn’t always glamorous, and he had his fair share of controversy, but he remains one of the most brilliant scientists ever to have lived.

16 December 2021
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