LOUIS PASTEUR: BIOGRAPHY, DISCOVERIES AND CONTRIBUTIONS TO SCIENCE - SCIENCE - 2025

Louis Pasteur was a scientist specializing in chemistry and biology, born in France in 1822. Among his most important discoveries are his contributions to the development of vaccines or the invention of the system for eliminating microorganisms in food that bears his name: pasteurization.

Despite not having been a very bright student during his childhood, his move to higher education meant a great change in his interests. He left behind his predilection for the arts to focus on the sciences, especially chemistry. He was a professor at several universities in his country.

This teaching work was combined with research throughout his life. She stood out so much that the government entrusted her with various field works, such as the eradication of a plague that was threatening the silkworm industry. Pasteur received great recognition for creating a vaccine against rabies.

This recognition obtained was not only within the scientific world, but also in the popular sphere. In fact, it was this support that allowed him to found the Louis Pasteur Institute, thanks to a national subscription. Soon this institution became a world reference in the study of infectious diseases.

Biography of Louis Pasteur

Early years

Louis Pasteur was born in the town of Dôle, France, on December 22, 1822. He spent his early years in his city of birth, where he completed his primary education. The future scientist did not stand out in those early years for being too interested in science, but his tastes were more focused on the arts.

It was his father, who worked as a tanner, who forced him to enroll at the Liceo de Besançon to complete high school. There, Pasteur obtained the baccalaureate of letters in 1840 and the one of sciences 2 years later.

High school and first jobs

At the end of this stage, he continued his training at the Ecole Normale Supérieure in Paris, although he did not last long in the center. After a year back in his city, he returned to Paris and, now, he has finished his studies.

It was during this period that he became interested in science and, although his first job was as a Physics teacher at the Lyceum in Dijon, he began to opt for chemistry. It was in this field that he presented his doctorate in 1847, under the direction of Dumas and Balard.

His first investigations dealt with racemic acid and paratartaric acid. Likewise, he developed an innovative -although erroneous- theory of molecular asymmetry.

Professional life

As previously mentioned, Pasteur began working as a teacher in 1848 at the Liceo de Dijon. At that time he married the daughter of the university rector, Marie Laurent, and obtained the chair of chemistry.

In 1854 he moved to Lille to teach the same subject at the city's university. In addition, he served for three years as dean of the Faculty of Sciences. Apart from his teaching work, in Lille he carried out important research on fermentation to improve the wine and beer industries in the area.

At the end of his term as dean, he returned to Paris. He first held the position of director of the science department at the École Normale and later became a professor of chemistry. He was there until 1875, and highlighted his academic polemic against supporters of the theory of spontaneous generation of life.

Silkworm disease

A commission from the French government sent him to the south of France to try to find a solution to an epidemic that was threatening the silkworm industry in the region.

The research carried out by Pasteur was essential to end the plague that affected the worms. During this assignment he received confirmation of his belief in the responsibility of pathogenic microorganisms in many infections. This was a step forward in developing his theory on microbial pathology.

Other investigations

Another event, in this case warlike, forced Pasteur to leave Paris in 1871. The civil war made him move to Clermont-Ferrand, where he did not stop his research.

Upon returning to the capital, his prestige led to a lifetime pension, in addition to his appointment as a member of the Academy of Medicine and the French Academy. Likewise, he was decorated with the country's Legion of Honor.

Among the most important contributions in that period are his research on cholera, which affected chickens and which was the first step in the creation of vaccines.

The vaccine

Other animal research, in this case on the anthrax disease that affected cattle, led Pasteur to advance the development of these vaccines. In 1881 he discovered how to inoculate animals with weakened pathogens to strengthen the immune system. Soon after, the same principle served him to create the rabies vaccine.

These contributions made him so famous that a popular collection helped him open the Pasteur Institute in 1888. From this research center he continued studying infectious diseases.

Death

The scientist's health had been greatly weakened since the hemiplegia he suffered in 1868. The awards and recognitions were constant in recent years, including an impressive tribute at the Sorbonne on the occasion of his 70 years of life.

Pasteur died three years after this, on September 28, 1895, in the town of Marnes-la-Coquette.

Discoveries and contributions

Louis Pasteur in his laboratory, painting by A. Edelfeldt in 1885.

Pasteurization

This process that bears his name has saved millions of lives around the world since its inception. The most widely accepted theory at the time was that no organism participated in fermentation as a chemical process. However, while conducting research on wine, Pasteur discovered that two types of yeast were the key to that process.

One type of yeast produced alcohol and the other caused the appearance of lactic acid, guilty of souring the drink. After that discovery, it was proposed to eliminate the cause of the deterioration of the wine.

To do this, he introduced the liquid into airtight containers and quickly heated it up to 44 degrees. This simple procedure made it free of harmful microorganisms. Since then, this heating method has been used to make many foods safer.

Vaccine development

Like other important discoveries in the history of science, the first vaccine was discovered by chance. Pasteur was studying how the bacteria that cause fowl cholera were transmitted, inoculating it in healthy animals to investigate its effects.

According to the known story, the scientist went on vacation and left his assistant the task of infecting some chickens with the bacteria before he also took his vacation break.

However, the assistant forgot to do so, and when the two returned to work a month later, the bacteria culture was severely weakened. Still, they used it to inoculate a group of birds and they survived the infection.

This gave Pasteur the origin idea of ​​the vaccine. He exposed those surviving animals to normal bacteria, and because they had created an immune response, they survived the disease. After this, he experimented with other diseases caused by bacteria, such as anthrax in cattle, being a success.

Rabies vaccine

Rabies was a deadly disease that caused many victims in animals and humans infected by them. Pasteur began work on a possible vaccine using rabbits to find out what the causative pathogen was.

It is said that in 1885 a child bitten by dogs with the disease came to help him. Until that moment, the scientist had only tested the results of his research with dogs and, furthermore, since he was not a doctor, he risked legal consequences if something went wrong.

Faced with the certain death of the boy and, after consulting other colleagues, Pasteur decided to use his vaccine. Fortunately, the treatment worked and the boy made a full recovery.

Research on fermentation

Closely related to pasteurization, this discovery took him several years from the 1950s to the 19th century. He was the first to show that fermentation was initiated by living organisms, specifically by yeasts.

Importance of temperature in controlling the growth of bacteria

His research with chickens was not only important for the development of the vaccine. They also helped him to observe how temperature was important for the growth of bacteria.

Pasteur observed that anthrax did not survive in the blood of these birds and discovered that it was because their blood is at a higher temperature than that of other mammals.

Rediscovered anaerobiosis

In 1857, while studying fermentation, Pasteur discovered that the process could be stopped by introducing air into the fluid.

With this observation, he concluded that there was a life form capable of existing even without oxygen. Thus, he developed the concepts of aerobic life and anaerobic life.

In practical terms, this led to the development of the so-called Pasteur Effect, which inhibits fermentation by oxygen.

Saved the European silk industry

While working on his germ theory, in 1865, Pasteur discovered that a serious silkworm disease, pebrine, was caused by a small microscopic organism that is now known as Nosema bombycis.

By then the French silk industry was seriously affected and the disease was beginning to spread to other areas. Through a method invented by Pasteur, it was possible to identify which silkworms were infected and stop the spread of this plague.

Demonstrated the importance of temperature in controlling the growth of bacteria

Through his research with hens infected with anthrax splenic fever, which remained immune to the disease, he was able to show that the bacteria that produced anthrax were not able to survive in the bloodstream of the hens.

The reason was that their blood is 4 degrees Celsius above the blood temperature of mammals such as cows and pigs.

With anthrax the leading cause of death in grazing animals and also an occasional cause of death in humans, the development of a vaccine against this bacterium produced a dramatic drop in the range of infections.

Determined the existence of asymmetry in the crystals

Louis Pasteur in 1849, while working as a physics teacher at the Tournon school, studied how certain crystals can affect light.

To do this, he solved a problem with tartaric acid crystals, which polarized light in different ways - some rotating clockwise and others counterclockwise.

With this, Pasteur discovered that the tartaric acid molecule is asymmetric and can exist in two different but similar forms, as in the case of two gloves, the left and the right that are similar but not the same.

In addition to this, he continued to study the relationship between molecular configuration and crystal structure, and with this he was able to realize that asymmetry is a fundamental part of living matter and living beings.

He proved the veracity of the germ theory

Previously, fermentation and putrefaction phenomena were thought to be spontaneous.

For a long time, this theory of spontaneous generation was supported by various scientists of his time, including the naturalist John Tuberville Needham and the French naturalist Georges-Louis Leclerc, Earl of Buffon.

Others like the Italian physiologist Lazzaro Spallanzani thought that life could not be generated from dead matter.

Louis Pasteur decided to clarify this dispute through his germ theory, and for this he carried out a simple experiment: sterilizing a meat broth by boiling it in a "gooseneck bottle". This prevented any type of contaminant from entering, because it has a long neck that traps particles and contaminants before they enter the body of the bottle where the broth was.

When the neck of the bottle was broken and the broth was re-exposed to an unsterilized environment, it turned dark, indicating microbe contamination.

This experiment showed that the theory of spontaneous generation was not correct, since while the broth was in the bottle it remained sterile.

This experiment not only clarified the philosophical problem of the origin of life, but was also the basis for the foundation of the science of bacteriology.

He founded the Louis Pasteur Institute

To continue the legacy of his research, Pasteur founded the institute that bears his name in 1887.

Today it is one of the main research centers, with more than 100 research units, 500 permanent scientists and approximately 2,700 people working in this field.

The achievements of the Pasteur Institute are a greater understanding of diseases of infectious origin, and it has made important contributions in the field of treatments, prevention and cures of infectious diseases that exist until today such as diphtheria, typhoid fever, tuberculosis, among others.

References

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