Pasteur, Louis (1822–1895)
Although Louis Pasteur was educated as a chemist, his work had a tremendous impact on medicine. To combat the souring of alcohol or dairy products caused by microorganisms, he invented the technique (now called pasteurization) of heating the beverage, thereby killing any bacteria. Pasteur also disproved the erroneous theory of spontaneous generation, which held that substances could produce germs of their own accord. Pasteur showed that germs instead were introduced into a substance from the outside. His research on fermentation and spontaneous generation led him to propose the germ theory of diseases, which laid the foundation for the field of microbiology. Later in his life Pasteur developed vaccines for chicken cholera, anthrax, and rabies.
Born on December 27, 1822, Pasteur was the only son of Jean-Joseph and Jean-Étiennette Pasteur. When he was four his family moved from his birthplace of Dôle, France, to the town of Arbois, where he spent the rest of his childhood.
Pasteur attended the Collège d'Arbois and the Collège Royal de Besancon from 1831 until 1840. In preparing for his entrance exams to the École Normale in Paris he took classes at the Sorbonne with the famed chemist Jean-Baptiste Dumas. He entered the École Normale in 1843; there he received his doctorate with a focus on physics and chemistry in 1847.
Pasteur became a professor of chemistry at Strasbourg in 1849. His early work with d-tartrate crystals ultimately led to the discovery of molecular asymmetry. In 1854 he took a faculty position at Lille, where he began to explore the fermentation process that occurs in alcohol and milk. His endeavors in this field had the practical outcome of helping to preserve the French beer- and wine-making industry. Moreover his research demonstrated that the production of alcohol during fermentation was caused by yeast and that souring was due to the presence of additional organisms (namely, bacteria) in the beverage. He found that when alcohol—and likewise milk—was heated, this undesirable souring would not take place because the higher temperatures destroyed the bacteria. In 1857 Page 569 | Top of ArticlePasteur was named the director of the École Normale in Paris.
Pasteur applied the results of his fermentation work to the hotly contested topic of spontaneous generation. In 1862 he published his renowned text Note on Organized Corpuscles That Exist in the Atmosphere, which demonstrated that germs can be introduced to a substance only from an external source. He derived his conclusion from experiments involving a sterilized, fermentable fluid kept in two different kinds of vessels. One container, a swan-necked flask, did not allow dust or microorganisms to enter; the other container did. The fluid in the swan-necked flask remained free of germs, whereas its counterpart was quickly contaminated. These experiments led him to propose his germ theory of disease: Illness arises as a result of germs that attack the body from outside.
After working at the Sorbonne from 1867 to 1874, Pasteur returned to the École Normale, where he undertook pioneering research into human diseases. In 1880 he inadvertently found a vaccine for chicken cholera. He injected chickens with cholera bacilli that had been accidentally left out for some time. Not only did the chickens not become ill; they were also able to withstand exposure to fresh cholera bacilli. By 1882 he had developed a vaccine against anthrax, which he publicly and successfully tested at Pouilly-le-Fort. In 1885 Pasteur used his newly created rabies vaccine to save a nine-year-old boy, Joseph Meister, who was badly infected. Like his chicken cholera vaccine, Pasteur's rabies vaccine inoculated against infection and even treated the disease after it had been contracted. In eradicating the threat of rabies, Pasteur became a national hero. The French government funded the founding of the Pasteur Institute, and Pasteur was made its director.
Pasteur received countless honors and awards for his work. In 1881 he was given the Grand Cross of the Legion of Honor, and he was elected to the French Academy in 1882. Pasteur's contributions to the field of medicine were profound and lasting: His rabies vaccines motivated the next generation to seek other vaccines to prevent other diseases, and his germ theory paved the way for Lister'sadvances in antiseptic surgery and for other systematic research to combat infectious diseases.