1822-1895

French chemist and biologist who founded the science of microbiology. He developed the germ theory of disease that illustrated how diseases are spread by bacteria. Pasteur also proved that microbes could be weakened in a laboratory and then placed in an animal's body to create resistance, or immunity, to the microbe. Pasteur used this process of vaccination to protect sheep against the deadly anthrax disease before going on to develop vaccines for human diseases, including rabies. In the early 1960s, Pasteur invented pasteurization, the process that prevents milk from souring by heating it to a high temperature and pressure before bottling.