Childhood: Robert Koch was born on December 11, 1843, in Clausthal, Germany. His father was a mining engineer. At the age of five, he taught himself to read using newspapers; this was, however, only a foreshadowing of his amazing intelligence. He attended high school in his hometown and showed heavy leanings towards biology.

At University: There were two professors at his university who helped him to begin the intellectual process that would lead to his Nobel Prize winning work. The first was Friedrich Wohler, the first chemist to synthesize an organic compound from an inorganic substance (1828). The second was Jacob Henle, who believed that infectious diseases were caused by living, parasitic organisms (published in 1840).

A Career: After gaining his M.D. degree in 1866, Koch went to Berlin for six months. Then he settled as Assistant in the General Hospital in Hamburg, as a doctor of general practice. In 1870 he volunteered for service in the Franco-Prussian War. From 1872-1880 he was District Medical Officer in Wollstein, and this is where he began to make his world-changing discoveries.

Anthrax: In 1863, Louis Pasteur had shown that anthrax was caused in sheep by the presence of rod-like bodies in the blood. However, little else about the epidemiology of the disease was known. In 1872, anthrax was killing off farm animals around Wollstein. Koch, cut off from libraries and laboratories, and having access only to research equipment that he himself acquired (aside from the microscope given to him by his wife), turned his four room house into a working laboratory.

Koch began to inoculate mice using anthrax bacilli taken from the spleens of animals dead of the disease. The animals that he inoculated did not die. Through these experiments, he clarified that the disease could be transmitted through the blood of infected animals.

Next, he performed experiments to determine whether anthrax bacilli that had never been in contact with any kind of animal could cause the disease. He obtained pure cultures of the bacteria by growing it on the aqeuous humor of an ox's eye. He then observed the multiplication of the bacteria and noted that it can produce, from within itself, a rounded spore that can withstand poor conditions (low temperature, for instance, or lack of oxygen). He grew the bacilli for several generations, and yet it still survived. This explained why the disease could lie dormant in a pasture for years and then unexplainedly spring up in livestock again.

Because of this work, Koch was noticed by Ferdinand Cohn, the Professor of Botany at the University of Breslau. He called a meeting of his colleagues and Koch was invited to perform a demonstration of his work in 1876. He became famous because of this, but his work remained controversial. His findings would not be fully believed until Louis Pasteur created an anthrax vaccine in 1882.

Research Methods: Koch was appointed to the Imperial Health Offices in Berlin to give advice on hygiene and public health. He used several important research techniques:

  • He stained bacteria with dye to follow it under a microscope.
  • He was the first to cultivate pure strains of bacteria on agar, in the dishes named for his contemporary and colleague Petri. In 1882 he discovered the tuberculosis bacteria using this method.
  • He also developed an ingenious method for creating "pure"-- not cultivated from an infected animal-- strains of bacilli. This involved growing them over generations in petri dishes until only one exact type, rather than individual variations, remained.

Koch's Postulates:

  • The organism is discoverable in every instance of the disease.
  • Extracted from the body, the germ could be produced in a pure culture, maintainable over several microbial generations.
  • The disease can be reproduced in experimental animals through a pure culture removed by numerous generations from the organisms initially isolated.
  • The organism can be retrieved from the inoculated animal and cultured anew.


In 1883, Koch was sent to Egypt as Leader of the German Cholera Commission. He was to investigate an outbreak of cholera there. His research was frustrated by the cessation of the outbreak, and so he travelled to India (where there always seemed to be an outbreak of cholera) and was able to discover several bacilli, including amebic dysentery and two different strains of conjunctivitis, and cholera. He also discovered that cholera was transmitted via drinking water, food, and clothing. He formulated rules for the control of cholera epidemics that were approved by the Great Powers of Dresden and which are still in place today. He also received a prize of 100,000 German Marks.


After his discovery of the bacilli, Koch sought to find a cure or inoculation. He made a liquid preparation called tuberculin, but it did not work, and damaged his credibility.

Later Studies:

The Nobel Prize: He was awarded it in 1905 for Physiology and Medicine.

His Family: In 1866 he married Emmy Fraats, and together they had one child, Gertrude (1865). In 1893 Koch married Hedwig Freiberg. He died on May 27, 1910, in Baden-Baden.

For his Nobel Prize Acceptance Speech, see Robert Koch's Nobel Prize Acceptance Speech: The current state of the struggle against tuberculosis which I have noded separately because it is exceptionally long.

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