Louis Pasteur | Science History Institute

Louis pasteur biography

Louis Pasteur (1822-1895) is revered by his successors in the life sciences as well as by the general public. in fact, his name served as the basis for a household word: pasteurized.

His research, which showed that microorganisms cause both fermentation and disease, supported the germ theory of disease at a time when its validity was still in question. In his continuing search for disease treatments, he created the first vaccines for avian cholera; anthrax, a major livestock disease that has recently been used against humans in germ warfare; and the dreaded rage.

early years and education

Pasteur was born in Dole, France, the middle child of five children in a family that had been leather tanners for generations. The young Pasteur’s gifts seemed to be more artistic than academic until near the end of his high school years. Spurred on by the encouragement of his mentors, he undertook rigorous studies to make up for his academic deficiencies in order to prepare for the École normale supérieure, the famous Paris teachers’ college. he earned his master’s degree there in 1845 and his doctorate in 1847.

study of optical activity

While waiting for a suitable appointment, Pasteur continued to work as a laboratory assistant at the École normale. there he made further progress in the research he had begun for his doctoral thesis: investigating the ability of certain crystals or solutions to rotate plane-polarized light clockwise or counterclockwise, that is, to exhibit “optical activity”. he was able to show that in many cases this activity was related to the shape of the crystals of a compound.

He also reasoned that there was a special internal arrangement in the molecules of said compound that bent light, an “asymmetrical” arrangement. This hypothesis occupies an important place in the early history of structural chemistry, the field of chemistry that studies the three-dimensional characteristics of molecules.

fermentation and pasteurization

pasteur secured his academic credentials with scientific papers on this and related research and was later appointed in 1848 to the strasbourg faculty of sciences and in 1854 to the lille faculty. there he began his studies on fermentation. Pasteur sided with the minority opinion among his contemporaries that each type of fermentation is carried out by a living microorganism. at the time, most believed that fermentation was spontaneously generated by a series of chemical reactions in which enzymes, not yet securely identified with life, played a key role.

in 1857 pasteur returned to the École normale as director of scientific studies. in the modest laboratory he was allowed to establish there, he continued his study of fermentation and fought long and hard battles against the theory of spontaneous generation. Prominent in early rounds of these debates were several applications of his pasteurization process, which he originally invented and patented (in 1865) to combat “diseases” in wine. He realized that these were caused by unwanted microorganisms that could be destroyed by heating the wine to a temperature between 60° and 100°C. the process was later extended to all kinds of other spoilable substances, such as milk.

germ theory

At the same time that Pasteur began his studies of fermentation, he took a view related to the cause of disease. he and a minority of other scientists believed that diseases arose from the activities of microorganisms: the germ theory. Opponents believed that illnesses, particularly the major killer diseases, arose in the first instance from a weakness or imbalance in the internal state and quality of the affected individual. In an early foray into the causes of particular diseases, in the 1860s, Pasteur was able to determine the cause of the devastating plague that had befallen the silkworms that were the foundation of the then-important silk industry in France. surprisingly, he discovered that the culprits were two microorganisms instead of one.

a new laboratory

pasteur, however, did not devote himself fully to the study of disease until the late 1870s, after several cataclysmic changes had shaken his life and that of the French nation. In 1868, in the midst of his silkworm studies, he suffered a stroke that partially paralyzed his left side. Soon after, in 1870, France suffered a humiliating defeat at the hands of the Prussians, and Emperor Louis Napoleon was overthrown. However, Pasteur successfully concluded with the new government the negotiations that he had initiated with the Emperor.

The government agreed to build him a new laboratory, relieve him of administrative and teaching duties, and give him a pension and a special reward to release his energies into disease studies.

attenuating microbes for vaccines: fowl cholera and anthrax

In his research campaign against the disease, Pasteur first worked to expand what was known about anthrax, but his attention quickly turned to avian cholera. this research led him to discover how to make vaccines by attenuating or weakening the microbe involved. Pasteur used to “refresh” the laboratory cultures he was studying, in this case, fowl cholera, every few days; that is, he restored their virulence by reintroducing them into laboratory chickens with the consequent attack of diseases and the death of the birds.

Months after the experiments, Pasteur left avian cholera cultures dormant while he went on vacation. when he returned and the same procedure was tried, the chickens did not get sick as before. Pasteur could have easily 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. surprisingly, the chickens survived and did not get sick; they were protected by a microbe attenuated over time.

Realizing that he had discovered a technique that could be extended to other diseases, Pasteur returned to his study of anthrax. Pasteur produced vaccines from weakened anthrax bacilli that could actually protect sheep and other animals. In public demonstrations at Pouilly-le-Fort before crowds of observers, twenty-four sheep, one goat, and six cows were subjected to a two-part course of inoculations with the new vaccine, on May 5, 1881, and again on May 17. meanwhile, a control group of twenty-four sheep, one goat, and four cows remained unvaccinated.

On May 31, all the animals were inoculated with virulent anthrax bacilli, and two days later, on June 2, the crowds assembled again. Pasteur and his collaborators arrived to great applause. the effects of the vaccine were undeniable: the vaccinated animals were all alive. of the control animals, all the sheep were dead except three staggering individuals who died by the end of the day, and the four unprotected cows were swollen and feverish. the only goat had also expired.

rage and the beginnings of the pasteur institute

pasteur then wanted to move on to the more difficult area of ​​human disease, in which ethical concerns weighed more heavily. he searched for a disease that affects both animals and humans so that most of his experiments could be done on animals, though here he, too, had strong reservations. Rabies, his chosen disease, had terrified the population for a long time, though it was actually quite rare in humans. Until the time of the pasteur vaccine, a common treatment for a rabid animal bite had been cauterization with a red-hot iron in the hope of destroying the unknown cause of the disease, which almost always developed after a period of time. incubation period typically long.

Rabies presented new obstacles to the development of a successful vaccine, mainly because the microorganism causing the disease could not be specifically identified; nor could it be grown in vitro (in the laboratory and not in an animal). As with other infectious diseases, rabies could be injected into other species and attenuated. rabies attenuation was first achieved in monkeys and later in rabbits. On July 6, 1885, Pasteur succeeded in protecting dogs, even those that had already been bitten by a rabid animal. He agreed with some reluctance to treat his first human patient, Joseph Meister, a nine-year-old boy who was otherwise doomed to near death. -sure death. success in this case and thousands more convinced an appreciative public around the world to make contributions to the institut pasteur. It officially opened in 1888 and continues as one of the world’s leading biomedical research institutions. its tradition of discovering and producing vaccines is continued today by the pharmaceutical company sanofi pasteur.

a great experimenter and innovative theorist

pasteur’s career shows that he was a great experimenter, far less concerned with the theory of disease and immune response than with directly treating disease by creating new vaccines. it is still possible to discern his notions on the most abstract subjects. he very soon linked the immune response to the biological, especially nutritional, requirements of the microorganisms involved; that is, the microbe or attenuated microbe in the vaccine exhausted its food source during its first invasion, making it difficult for the microbe to attack next. he later speculated that microbes could produce toxic chemicals themselves that circulated throughout the body, thus pointing to the use of toxins and antitoxins in vaccines. He lent support to another point of view by welcoming the Élie Metchnikoff Pasteur Institute and his theory that “phagocytes” in the blood (white blood cells) cleanse the body of foreign matter and are the main agents of immunity.

The information in this bio was last updated on December 14, 2017.

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