Louis Pasteur

Louis Pasteur (1822 to 1895) was a French chemist, pharmacist and microbiologist, renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization, the last of which carries his name. His early chemical work on the asymmetry of crystals and on sodium ammonium tartrate began the field of optical isomerism. For agriculture and food his most lasting contribution was showing that the growth of micro-organisms was responsible for spoiling beverages such as beer, wine and milk, and that lactic acid made by a contaminating organism turned wine sour. He patented a heating process against the diseases of wine in 1865, and the method, called pasteurization, was soon applied to beer and milk. He also disproved the doctrine of spontaneous generation with sealed and open sterilized flasks, helped establish the germ theory of disease, and developed vaccines for anthrax and rabies. He directed the Pasteur Institute, established in 1887, until his death. His reputation is also tied to controversy, since a historical reassessment of his notebook found that he practiced deception to overcome his rivals.