Louis Pasteur (1822-95), the son of a tanner in southern France, became professor of chemistry at the Sorbonne in Paris.
He became interested in the process of fermentation and proved that it was caused by microorganisms. He soon demonstrated that each sort of fermentation is linked to the existence of a specific microorganism -- a living being that one can study by cultivation in an appropriate, sterile medium. This insight is the basis of microbiology. Pasteur dealt the death blow to the theory of spontaneous generation and developed germ theory. At the same time, he discovered the existence of life without oxygen: "Fermentation is the consequence of life without air." The discovery of anaerobic life paved the way for the study of germs that cause septicemia and gangrene, among other infections. Thanks to Pasteur, it became possible to devise techniques to kill microbes and to control contamination.
Emperor Napoleon III asked Pasteur to investigate the diseases afflicting wine which were causing considerable economic losses to the wine industry. Pasteur went to a vineyard in Arbois in 1864 to study this problem. He demonstrated that wine diseases are caused by microorganisms that can be killed by heating the wine to 55deg.C for several minutes. Applied to beer and milk, this process, called "pasteurization," soon came into use throughout the world.
The French government asked him to investigate a silkworm disease that was threathening to destroy the French silk industry. Within a couple of years he found two possible causes, a type of protozoa and a virus and developed a pesticide to control them.
In 1877, whilst studying the anthrax bacillus, Pasteur produced a vaccine for it. Around this time he also produced a vaccine for chicken cholera and is said to have saved the French chicken industry more money than what the country paid in damages after its war with Prussia in 1870!
From 1877 to 1887, Pasteur went on to discover three bacteria responsible for human illnesses: staphylococcus, streptococcus and pneumococcus.
Pasteur's crowning achievement was a vaccine for rabies, which had been all but incurable before. The work was not without danger for Pasteur and his assistants - they had to keep a large kennel full of mad dogs! On July 6, 1885, Pasteur tested his pioneering rabies treatment on man for the first time: the young Joseph Meister was saved.
The grateful nation built an institute in Pasteur's honour (Pasteur Institute aka. Institut Pasteur) in 1887. In accordance with Pasteur's wishes, the Institute was founded as a clinic for rabies treatment, a research center for infectious disease and a teaching center. It was there that he was buried and that research in bacteriology continues.
Pasteur's work is not simply the sum of his discoveries. It also represents the revolution of scientific methodology. Pasteur superimposed two indisputable rules of modern research: the freedom of creative imagination necessarily subjected to rigorous experimentation. He would teach his disciples:
"Do not put forward anything that you cannot prove by experimentation"
Louis Pasteur was a humanist, always working towards the improvement of the human condition. He was a free man who never hesitated to take issue with the prevailing yet false ideas of his time.
He ascribed particular importance to the spread of knowledge and the applications of research. In the scientist's lifetime, Pasteurien theory and method were put into use well beyond the borders of France.
Fully aware of the international importance of his work, Pasteur's disciples (the Pasteuriens) dispersed themselves wherever their assistance was needed. In 1891, the first Foreign Institut Pasteur was founded in Saigon (today Ho Chi Minh City, Vietnam) launching what was to become an international network of Pasteur Institutes.
Because he changed the world forever, his homeland and the world have long considered him a benefactor of humanity. In fact, some years after his death, the French held a referendum to determine who was the greatest man in the country's history; Pasteur won by a broad margin.
Over the last half of the 19th century, Pasteur's work revolutionized chemistry, agriculture, industry, medicine, surgery and hygiene. UNESCO recognized the centennial of Pasteur's death by designating 1995 to be the "The Year of Louis Pasteur".