Biography of Pasteur, the chemist father of microbiology who invented pasteurization

Louis Pasteurborn in 1822 and died in 1895, was one French scientist and chemistauthor of fundamental discoveries in the field of microbiology. Pasteur developed the process of pasteurization of foods (named in his honor) and definitively refuted the theory of spontaneous generation of microorganisms. Although he worked mainly in the field of agriculture and the food industry, he was able to test his theories also on humansPasteur’s discoveries brought enormous progress to medicine: they demonstrated that infectious diseases are transmitted through microorganismsfacilitated the introduction of the Sterilization of instruments used in surgical operations and allowed the creation of new vaccines. Let’s see his life in brief.

Birth and studies

Louis Pasteur was born in Dole, in the French Jura, in 1822. He belonged to a family of humble originsbut he still managed to attend school, demonstrating great aptitude for studies. After graduating from Besançon, he entered the prestigious Higher Normal School of Paris, where he graduated in physics and in chemistry. He taught physics briefly at the Lycée de Dijon and in 1848 became professor of chemistry at the University of Strasbourg. In the years that followed he made his most important discoveries.

Microbiology in the Time of Pasteur and the Theory of Spontaneous Generation

At the time of Pasteur, science knew little about microorganisms. There was no consensus among scientists that bacteria were carriers of diseases. A very widespread theory, in fact, wanted epidemics to be caused by miasmasthat is, exhalations present in the air. Another unfounded theory was also widespread, that of spontaneous generationaccording to which microorganisms arise “spontaneously” from inanimate elements. The theory of spontaneous generation was opposed by the idea of biogenesiaccording to which microorganisms can only be generated from other microorganisms, just like all other living beings.


Pasteur was strongly opposed to spontaneous generation and in 1864 the he definitively refuted. He performed an experiment by filling containers with liquids that had long necks: after sealing them, he heated the liquids inside, killing the microorganisms, and demonstrated that they would only form again when the neck of the container was broken. In other words, the microorganisms had to enter from the outside. Thanks to the demonstration of the correctness of the theory of biogenesis, Pasteur obtained the prize of the French Academy of Sciences.

The pasteurization process

Starting from the biogenesis of microorganisms, Pasteur introduced the process that bears his name: pasteurization. He realized that some foods, such as milk, deteriorated due to the action of microorganisms. Consequently, if the bottles containing them were heated, the germs could be killed and the quality of the drinks could be preserved, which could last longer. Pasteurization proved useful not only for milk, but also for other drinks, such as wine and beer.

Consequences of Pasteur’s discoveries

Thanks to Pasteur’s studies, the Germline theory of infectious diseasesthat is, the one according to which the contagion is transmitted through microorganisms, which “travel” from one human being to another (or from animals to humans) through the air or physical contact.

Pasteur’s discoveries, moreover, were very useful for the introduction of theantisepsithat is, the sterilization of surgical instruments in the operating room: by demonstrating that contagion occurred through microorganisms, Pasteur pushed surgeons to sterilize their instruments, drastically reducing infections and deaths following operations.

Pasteur and vaccines

Pasteur also played an important role in the development of vaccines. He was not the inventor, because since the end of the eighteenth century an English doctor, Edward Jennerhad created a vaccine against smallpox, but he also introduced great innovations. He demonstrated, in fact, that the vaccines that could be created directly from pathogenic microorganisms. He carried out many tests on animals and in 1885 he had the opportunity to experiment with the vaccine against anger – a disease that is almost 100% fatal – on a nine-year-old boy bitten by a dog suffering from rabies, managing to save him. Pasteur also conducted studies and discoveries on other topics, such as beer fermentation, chicken cholera, and silkworm diseases.

Vaccination of a boy under Pasteur's eyes

Pasteur’s Fame and Death

Pasteur had to fight against doctors and scientists who did not want to abandon the old theories of spontaneous generation and miasmas. He also had to sustain a tough controversy with Robert Kocha German scientist who also made a great contribution to microbiology. Over the years, however, Pasteur managed to demonstrate the validity of his ideas and to gain great fame, to the point that in 1888 in Paris he was born an institution that bears his name. He died in 1895 due to a stroke.