LOUIS PASTEUR (1822-1895)

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LOUIS PASTEUR (1822-1895): Louis Pasteur was a French chemist, biologist and microbiologist who discovered the process of mild heating of food (milk) known as pasteurization. Pasteur was the first to report the role of microorganisms in fermentation in 1848; and he contributed greatly in the discovery of vaccination. Pasteur was the first to create and use vaccines; and he developed vaccines for anthrax and rabies diseases caused by Bacillus anthracis and rabies virus respectively. Though a trained chemist, Pasteur was also one of the first scientists to recognize the significance of optical isomers, and he emerged one of the greatest biologists and chemist of the 19th century. As a Professor of Chemistry, Louis Pasteur achieved distinction in organic chemistry for his discovery that tartaric acid (a four-carbon organic compound) forms two different types of crystals. In the field of microbiology, he also showed that pebrine disease of silkworm was caused by a protozoan parasite. In 1857, he unraveled the mystery of sour wine and showed that microorganisms (bacteria) were responsible for the spoilage of wine and other food products. Louis Pasteur demonstrated that alcoholic fermentations were as a result of microbial activity, and that some microorganisms could decrease alcohol yield and sour the product. Pasteur also showed that some fermentations were aerobic while others where anaerobic.


Pasteur also developed the process of pasteurization ‘to preserve wine during storage’ by showing that mild-heating of milk could kill microorganisms in broth. Pasteur firmly disproved the doctrine of spontaneous generation by his swan-necked flask experiment. He isolated the causative agents of cholera and rabies and subsequently developed vaccines for rabies, cholera, chickenpox and anthrax. Louis Pasteur also proposed germ theory of disease and he also discovered the existence of life in the absence of free oxygen (anaerobic growth). His breakthroughs in microbiology helped solidify the concept of the germ theory of disease, whose principles were being developed at about this time by Robert Hooke and other microbiologists. Pasteur in 1880 developed a method of weakening a virulent pathogen, and using same to immunize individuals. His work established the roadmap for inoculating people with attenuated microorganisms as a way of protecting them from diseases caused by specific pathogenic microorganisms. And this paved the way and laid the foundation for the principles of immunization/vaccination which is widely used today to prevent infectious disease outbreak and spread in human and animal population.

Further reading

Brooks G.F., Butel J.S and Morse S.A (2004). Medical Microbiology, 23rd edition. McGraw Hill Publishers. USA. Pp. 248-260.

Madigan M.T., Martinko J.M., Dunlap P.V and Clark D.P (2009). Brock Biology of microorganisms. 12th edition. Pearson Benjamin Cummings Publishers. USA. Pp.795-796.

Nester E.W, Anderson D.G, Roberts C.E and Nester M.T (2009). Microbiology: A Human Perspective. Sixth edition. McGraw-Hill Companies, Inc, New York, USA.

Prescott L.M., Harley J.P and Klein D.A (2005). Microbiology. 6th ed. McGraw Hill Publishers, USA. Pp. 296-299.

Singleton P and Sainsbury D (1995). Dictionary of microbiology and molecular biology, 3d ed. New York: John Wiley and Sons.

Slonczewski J.L, Foster J.W and Gillen K.M (2011). Microbiology: An Evolving Science. Second edition. W.W. Norton and Company, Inc, New York, USA.

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