Louis Pasteur

Louis Pasteur (December 27 1822 – September 28 1895) was a French microbiologist and chemist. He is known to the general public for his demonstration of the germ theory of disease and his development techniques of inoculation, most notably the first vaccine against rabies; however, he also made a major discovery in the field of chemistry, regarding asymmetric molecules and the polarization of light.

Germ theory

Louis Pasteur demonstrated that the fermentation process is caused by the growth of microorganisms, and that the growth of microorganisms in nutrient broths is not due to spontaneous generation.

Related Topics:
Fermentation - Microorganism - Spontaneous generation

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He exposed boiled broths to air in vessels that contained a filter to prevent all particles from passing through to the growth medium and even in vessels with no filter at all, with air being admitted via a long tortuous tube that would not allow dust particles to pass. Nothing grew in the broths; therefore, the living organisms that grew in such broths came from outside, as spores on dust, rather than being spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported germ theory.

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While Louis Pasteur did not develop germ theory (Girolamo Fracastoro, Friedrich Henle and others had suggested it earlier), he conducted experiments that clearly indicated its correctness and managed to convince most of Europe that it was true.

Related Topics:
Germ theory - Girolamo Fracastoro - Friedrich Henle - Europe

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Pasteur's research also showed that some microorganisms contaminated fermenting beverages. With this established, he invented a process in which liquids such as milk were heated to kill all bacteria and molds already present within them. He and Claude Bernard completed the first test on April 20, 1862. This process was soon afterwards known as pasteurization.

Related Topics:
Claude Bernard - April 20 - 1862 - Pasteurization

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Beverage contamination led Pasteur to conclude that microorganisms infected animals and humans as well. He proposed preventing the entry of microorganisms into the human body, leading Joseph Lister to develop antiseptic methods in surgery.

Related Topics:
Joseph Lister - Antiseptic - Surgery

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In 1865, a disease called pebrine was killing great numbers of silkworms. Pasteur worked several years proving that it was a microbe attacking silkworm eggs which caused the disease, and that eliminating this microbe within silkworm nurseries would eradicate the disease.

Related Topics:
1865 - Pebrine - Silkworm

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Pasteur also discovered anaerobiosis - that some microorganisms can develop and live without air or oxygen.

Related Topics:
Anaerobiosis - Oxygen

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