Louis Pasteur : biography

Allegations of deception

In 1995, the centennial of the death of Louis Pasteur, the New York Times ran an article titled "Pasteur’s Deception". After having thoroughly read Pasteur’s lab notes, the science historian Gerald L. Geison declared Pasteur had given a misleading account of the preparation of the anthrax vaccine used in the experiment at Pouilly-le-Fort.See Gerald Geison, The Private Science of Louis Pasteur, Princeton University Press, 1995. ISBN 0-691-01552-X. May 1995 NY Times Max Perutz published a vigorous defense of Pasteur in the New York Review of Books.Dec. 21, 1995 NY Review of Books , letters

Research contributions

Molecular asymmetry

Pasteur separated the left and right [[crystal shapes from each other to form two piles of crystals: in solution one form rotated light to the left, the other to the right, while an equal mixture of the two forms canceled each other’s effect, and does not rotate the polarized light.]] In Pasteur’s early work as a chemist, he resolved a problem concerning the nature of tartaric acid (1848).L. Pasteur (1848) "Mémoire sur la relation qui peut exister entre la forme cristalline et la composition chimique, et sur la cause de la polarisation rotatoire" (Memoir on the relationship which can exist between crystalline form and chemical composition, and on the cause of rotary polarization)," Comptes rendus de l’Académie des sciences (Paris), vol. 26, pages 535-538.L. Pasteur (1848) (On the relations that can exist between crystalline form, and chemical composition, and the sense of rotary polarization), Annales de Chimie et de Physique, 3rd series, vol. 24, no. 6, pages 442-459.George B. Kauffman and Robin D. Myers (1998) The Chemical Educator, vol. 3, no. 6, pages (?).H. D. Flack (2009) Acta Crystallographica, Section A, vol. 65, pages 371-389.Joseph Gal: Louis Pasteur, Language, and Molecular Chirality. I. Background and Dissymmetry, Chirality 23 (2011) 1−16. A solution of this compound derived from living things (specifically, wine lees) rotated the plane of polarization of light passing through it. The mystery was that tartaric acid derived by chemical synthesis had no such effect, even though its chemical reactions were identical and its elemental composition was the same. This was the first time anyone had demonstrated chiral molecules.

Germ theory of fermentation

Pasteur demonstrated that fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is due not to spontaneous generation, but rather to biogenesis (Omne vivum ex vivo "all life from life").

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 unless the flasks were broken open, showing that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. This was one of the last and most important experiments disproving the theory of spontaneous generation.

While Pasteur was not the first to propose the germ theory (Girolamo Fracastoro, Agostino Bassi, Friedrich Henle and others had suggested it earlier), he developed it and conducted experiments that clearly indicated its correctness and managed to convince most of Europe that it was true. Today, he is often regarded as the father of germ theory.

Pasteur’s research also showed that the growth of micro-organisms was responsible for spoiling beverages, such as beer, wine and milk. With this established, he invented a process in which liquids such as milk were heated to kill most bacteria and moulds already present within them. Claude Bernard and he completed the first test on April 20, 1862. This process was soon afterwards known as pasteurization.