Koch, (Heinrich Hermann) Robert (1843–1910)

German bacteriologist who was awarded a Nobel Prize for Physiology or Medicine in 1905 for his investigations and discoveries in relation to tuberculosis. Koch and his assistants devised the techniques for culturing bacteria outside the body, and formulated the rules for showing whether or not a bacterium is the cause of a disease.

His techniques enabled him to identify the bacteria responsible for tuberculosis (1882), cholera (1883), and other diseases. He investigated anthrax bacteria in the 1870s and showed that they form spores which spread the infection.

Koch was a great teacher, and many of his pupils, such as Shibasaburō Kitasato, Paul Ehrlich, and Emil von Behring, became outstanding scientists.

Koch was born near Hannover and studied at Göttingen. He began research in the 1870s while working as a district medical officer. In 1879 he was appointed to the Imperial Health Office in Berlin to advise on hygiene and public health. He was professor at Berlin 1885–91, when he became director of the newly established Institute for Infectious Diseases, but he resigned in 1904 and spent much of the rest of his life advising other countries on ways to combat various diseases.

Koch experimented with various dyes and found some that stain bacteria and make them more visible under the microscope. He also devised methods of separating one type of bacteria from a mixture, and of culturing bacteria on gelatin. Koch and his assistants showed that steam is more effective than dry heat in killing bacteria.

Koch also showed that rats are vectors of bubonic plague and that sleeping sickness is transmitted by the tsetse fly.