born Dec. 11, 1843, Clausthal, Hannover
died May 27, 1910, Baden-Baden, Ger.
German physician.
As the first to isolate the anthrax bacillus, observe its life cycle, and develop a preventive inoculation for it, he was the first to prove a causal relationship between a bacillus and a disease. He perfected pure-culture techniques, based on tuberculosis organism and established its role in the disease (1882). In 1883 he discovered the causal organism for {{link=cholera">cholera and how it is transmitted and also developed a vaccination for rinderpest . Koch's postulates remain fundamental to pathology: the organism should always be found in sick animals and never in healthy ones; it must be grown in pure culture; the cultured organism must make a healthy animal sick; and it must be reisolated from the newly sick animal and recultured and still be the same. Awarded a Nobel Prize in 1905, he is considered a founder of bacteriology.