Louis Pasteur
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Introduction
Although regarded as one of the greatest scientists in history, Louis Pasteur was not a particularly good student. He did, however, show an aptitude for mathematics and painting in his youth. At the time declaring his ambition to become a professor of the 'fine arts'.
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Early Life
Pasteur, born on 27 December 1822 in the eastern French town of Dole, was the son of a tanner who was a veteran of Napoleon's grande armee. His family moved to Arbois when Louis was still young where he attended primary and secondary schools.
In 1840 he gained a BA degree from the Royal College in Besancon and a BSc in 1842. The following year he entered the Ecole Normale Superieure in Paris to study chemistry. 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.
In 1848 he became professor of Physics at Dijon Lycee, but in 1849 accepted the post of Professor of Chemistry at the University of Strasbourg. It was here, on May 29 1849, that he married Marie Laurent, daughter of the rector of the university. They were to have five children, only two of whom survived childhood.
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Academy of Science
| Pasture first gained recognition in 1848, at the age of 26, when he presented a paper before the Paris Academy of Sciences on the optical activity of stereoisomers. His discoveries arose out of a crystallographic investigation of tartaric acid, an acid formed in grape fermentation. He reported that tartic acid came in two molecular forms, one that rotated polarised light to the right and the other, mirror image, that rotated light to the left. He also showed that one form can be assimilated by living microorganisms whereas its opposite cannot.Pasteur became dean of the new science faculty at Lille University in 1854. At Lille he demostrated his belief that a relationship should exist between theory and practice, by conducting his regular students around large factories and organising evening classes for young workmen of the industrial city. |
Louis Pasteur (1822-85) in his laboratory
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Study of Fermentation
While at Lille University, Pasteur received a query from an industrialist on the production of alcohol from beet sugar. Apparently the beer was going sour after fermentation. Thus began the biological investigations, for which he is best known.
Pasteur began his studies of fermentation where once again he encountered, in liquid form, his right and left compounds. He examined the problem of lactic fermentation and showed yeast to be an organism capable of reproducing itself without free oxygen. This became known as the Pasteur effect. He showed that fermentation involved microorganisms, and for the process to be alcohol-producing, rather than lactic-acid producing, the correct type of yeast need to be used. To prevent souring of the wine during the ageing process, Paseur realised that the the wine had formed it must be gently heated to 50°C/122°F. This heating process is today called Pasteurization.
He was elected to the Academy of Sciences in 1862, and the following year a chair at the École des Beaux-Arts was established for him for a new and original program of instruction in geology, physics, and chemistry applied to the fine arts. However, his interest, and engagement in research, caused him to give up the post in 1867. With the support of Napoleon 3 the same institution created for him a laboratory of physiological chemistry.
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Spontaneous Generation
He now turned his attention to a controversy of the time, namely spontaneous generation. Pasteur recognised the fact that both lactic and alcohol fermentations were hastened by exposure to air. This led him to wonder whether his invisible organisms were always
present in the atmosphere or whether they were spontaneously generated. Pasteur was able to show that air contained spores of living organisms. When they were placed into nutrient broth the organisms reproduced. When he now boiled the broth in a special 'swan knecked' container, that allowed air in but kept dust out, the broth remained free of living organisms. This simple experiment helped disproved the theory of spontaneous generation.
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Silkworm Breeding
In 1865 the silk industry in France was threatened by disease that was killing the silkworm. The government commisioned Pasteur to find the cause. He moved to the south of France, the centre of silkworm breeding, to carry out his investigations. After three years he was able to anounce that he had found the parasite that was infecting the worms. One of his recomendations was the isolation and destruction of all infected silkworms. By following his advice the industry eliminated the disease.
This work stimulated further the interest of Pasteur in infectious disease. Ideas were now beginning to formulate in his mind, they were to eventually lead to the most important single medical discovery of all time, the 'germ theory' of disease.
Pasteur was partially paralyzed in 1868 and applied for retirement from the university. He did, however, continue his researches. He was elected to the Academy of Medicine in 1873 and in 1874 the French Parliament provided him with an award to ensure his material security. It also allowed him to continue with his work.
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Anthrax
Louis Pasteur in 1893 (Mansell Collection)
Pasteur's German rival, Robert Koch, had found that under cirtain conditions the rod shaped anthrax bacilli form heat resitant spores in the blood. They were later able to develop into bacilli. Koch deduced that it was through the spore that the disease was spread in fields. He had anounced his findings in 1876.
Pasteur experimented with Koch's bacillus, subjecting them to heat of different time periods, to find a way to attenuate their effect. He finally succeeded to produce a vaccine.
Pasteur had earlier observed that once animals, stricken with certain diseases, had recovered they were immune to further attacks. Firstly he isolated the germ of the disease and cultivated an attenuated form of the culture. This method was also applied to outbreaks of fowl pest in 1881.
In May 1881, Pasteur, characteristically, decided to stage a public demonstration, of his anthrax vaccine. He injected 24 sheep, 1 goat and 6 cows with the attenuated culture, leaving a similar number untreated. Two weeks later, he gave the test group a further and stronger injection. After another two weeks he gave all the animals a virulent anthrax culture. All the untreated animals died within three days. The demonstration gave germ theory a tremendous boost.
The process he was following was similar to that of the English physician Edward Jenner, in his method for vaccinating animals against cowpox.
Elected a member of the Académie Française in April 27 1882, Pasteur was now to undertake research that was to proved most spectacular of all, the preventative treatment of rabies.
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Rabies
His early research with the saliva of infected animals led him to the conclusion that the virus (not known at this time) was also present in the nerve centres. He demonstrated this by injecting a portion of the medulla oblongata, of a rabid dog, into that of a healthy animal, producing the symtoms of rabies. He used the dry tissue of infected animals to eventually obtain an attenuated form of the virus suitable for injection into humans.
On 6 July 1885 Pasteur used his vaccine to saved the life of Joseph Meister, a nine-year-old boy who had been bitten by a rabid dog. The outstanding success of the experiment opened the road to protection from the terrible disease.
In 1888 the Pasteur Institute was inaugurated in Paris. Its main purpose was the undertaking of fundamental research, prevention, and treatment of rabies. Although he was now failing in health Louis Pasteur headed the institute until his death on September 28 1895.
