Louis Pasteur Biography

(born Dec. 27, 1822, Dole, France—died Sept. 28, 1895, Saint-Cloud, near Paris) French chemist and microbiologist whose contributions were among the most varied and valuable in the history of science and industry. It was he who proved that microorganisms cause fermentation and disease; he who pioneered the use of vaccines for rabies, anthrax, and chicken cholera; he who saved the beer, wine, and silk industries of France and other countries; he who performed important pioneer work in stereochemistry; and he who originated the process known as pasteurization.

Early life and education

Pasteur was the descendant of generations of tanners. His great-grandfather had been an indentured labourer who had purchased his freedom. In his youth Pasteur showed little interest in anything but drawing and produced a number of pastels, portraits of his parents and friends. After attending primary and secondary schools in Arbois, where his family had moved, and then in Besançon, Pasteur earned his bachelier ès lettres (bachelor of arts) in 1840 and bachelier ès sciences (bachelor of science) at the Royal College in Besançon in 1842. The following year he was admitted to the École Normale Supérieure, the famous teachers' college in Paris. He became licencié ès sciences (master of science) in 1845, and, after acquiring an advanced degree in physical sciences, he won his docteur ès sciences (doctor of philosophy) in 1847. On May 22, 1848, at the age of 26, he presented before the Paris Academy of Sciences a paper reporting a remarkable discovery he had just made—that certain chemical compounds were capable of splitting into a “right” component and a “left” component, one component being the mirror image of the other. His discoveries arose out of a crystallographic investigation of tartaric acid, an acid formed in grape fermentation that is widely used commercially, and racemic acid—a new, hitherto unknown acid that had been discovered in certain industrial processes in the Alsace region. Both acids not only had identical chemical compositions but also had the same structure; yet they showed marked differences in properties. The German chemist Eilhardt Mitscherlich (1794–1863) had shown that while ordinary commercial tartaric acid affects the rotation of plane polarized light, the unknown acid had no such effect. With the help of his own chemical methods Pasteur supplied the clue to this enigma by showing that the salts of the racemic acid consisted of two types of crystals that were mirror images of one another (like right- and left-hand gloves). When separated the two types of crystals rotated plane polarized light to the same degree but in opposite directions (one to the right, or clockwise, and the other to the left, or counterclockwise). One of the two crystal forms of racemic acid proved to be identical with the tartaric acid of fermentation. As Pasteur showed further, one component of the racemic acid (that identical with the tartaric acid from fermentation) could be utilized for nutrition by micro-organisms, whereas the other, which is now termed its optical antipode, was not assimilable by living organisms. On the basis of these experiments, Pasteur elaborated his theory of molecular asymmetry, showing that the biological properties of chemical substances depend not only on the nature of the atoms constituting their molecules but also on the manner in which these atoms are arranged in space.