Life and Contributions of Robert Koch, Founder of Modern Bacteriology

Koch discovered the bacteria that cause tuberculosis and cholera

Portrait of Robert Koch
Portrait of Robert Koch, 1910.

U.S. National Library of Medicine

The German physician Robert Koch (December 11, 1843 — May 27, 1910) is considered the father of modern bacteriology for his work demonstrating that specific microbes are responsible for causing specific diseases. Koch discovered the life cycle of the bacteria responsible for anthrax and identified the bacteria that cause tuberculosis and cholera.

Early Years

Robert Heinrich Hermann Koch was born December 11, 1843 in the German town of Clausthal.

His parents, Hermann Koch and Mathilde Julie Henriette Biewand, had thirteen children. Robert was the third child and the oldest surviving son. Even as a child, Koch demonstrated a love of nature and showed a high degree of intelligence. He reportedly taught himself to read at the age of five.

Koch became interested in biology in high school and entered the University of Göttingen in 1862, where he studied medicine. While in medical school, Koch was highly influenced by his anatomy instructor Jacob Henle, who had published a work in 1840 proposing that microorganisms are responsible for causing infectious disease.

Career and Research

Upon earning his medical degree with high honors from the University of Göttingen in 1866, Koch practiced privately for a while in the town of Langenhagen and later in Rakwitz. In 1870, Koch voluntarily enlisted in the German military during the Franco-Prussian War.

He served as a doctor in a battlefield hospital treating wounded soldiers.

Two years later, Koch became the District Medical Officer for the city of Wollstein. He would hold this position from 1872 to 1880. Koch was later appointed to the Imperial Health Office in Berlin, a position he held from 1880 to 1885.

During his time in Wollstein and Berlin, Koch began his laboratory investigations of bacterial pathogens that would bring him national and world-wide recognition.

Anthrax Life Cycle Discovery

Robert Koch's anthrax research was the first to demonstrate that a specific infectious disease was caused by a specific microbe. Koch gained insight from prominent scientific researchers of his time, such as Jacob Henle, Louis Pasteur, and Casimir Joseph Davaine. Work by Davaine indicated that animals with anthrax contained microbes in their blood. When healthy animals were inoculated with the blood of infected animals, the healthy animals became diseased. Davaine postulated that anthrax must be caused by the blood microbes.

Robert Koch took this investigation further by obtaining pure anthrax cultures and identifying bacterial spores (also called endospores). These resistant cells can survive for years under harsh conditions such as high temperatures, dryness, and the presence of toxic enzymes or chemicals. The spores remain dormant until conditions become favorable for them to develop into vegetative (actively growing) cells capable of causing disease. As a result of Koch's research, the life cycle of the anthrax bacterium (Bacillus anthracis) was identified.

Laboratory Research Techniques

Robert Koch's research led to the development and refinement of a number of laboratory techniques that are still in use today.

In order for Koch to obtain pure bacterial cultures for study, he had to find a suitable medium on which to grow the microbes. He perfected a method for turning a liquid medium (culture broth) into a solid medium by mixing it with agar. The agar gel medium was ideal for growing pure cultures as it was transparent, remained solid at body temperature (37°C / 98.6°F), and bacteria did not use it as a food source. An assistant of Koch, Julius Petri, developed a special plate called a Petri dish for holding the solid growth medium.

Additionally, Koch refined techniques for preparing bacteria for microscope viewing. He developed glass slides and cover slips as well as methods for heat fixing and staining bacteria with dyes in order to improve visibility.

He also developed techniques for the use of steam sterilization and methods for photographing (micro-photography) bacteria and other microbes.

Koch's Postulates

Koch published Investigations into the Etiology of Traumatic Infective Diseases in 1877. In it, he outlined procedures for obtaining pure cultures and bacteria isolation methods. Koch also developed guidelines or postulates for determining that a particular disease is due to a specific microbe. These postulates were developed during Koch's study of anthrax and outlined four basic principles that apply when establishing the causative agent of an infectious disease:

  1. The suspected microbe must be found in all instances of the disease, but not in healthy animals.
  2. The suspected microbe must be isolated from a diseased animal and grown in pure culture.
  3. When a healthy animal is inoculated with the suspected microbe, the disease must develop.
  4. The microbe must be isolated from the inoculated animal, grown in pure culture, and be identical to the microbe obtained from the original diseased animal.

Tuberculosis and Cholera Bacteria Identification

By 1881, Koch had set his sights on identifying the microbe responsible for causing the deadly disease tuberculosis. While other researchers had been able to demonstrate that tuberculosis was caused by a microorganism, no one had been able to stain or identify the microbe. Using modified staining techniques, Koch was able to isolate and identify the responsible bacteria: Mycobacterium tuberculosis.

Koch announced his discovery in March of 1882 at the Berlin Psychological Society. News of the discovery spread, quickly reaching the United States by April of 1882. This discovery brought Koch world-wide notoriety and acclaim.

Next, as the head of the German Cholera Commission in 1883, Koch began investigating cholera outbreaks in Egypt and India. By 1884, he had isolated and identified the causative agent of cholera as Vibrio cholerae. Koch also developed methods for controlling cholera epidemics that serve as the basis for modern day standards of control.

In 1890, Koch claimed to have discovered a cure for tuberculosis, a substance he called tuberculin. Although tuberculin turned out not to be a cure, Koch's work with tuberculosis earned him the Nobel Prize for Physiology or Medicine in 1905.

Death and Legacy

Robert Koch continued his investigative research into infectious diseases until his health began to fail in his early sixties. A few years prior to his death, Koch suffered a heart attack brought on by heart disease. On May 27, 1910, Robert Koch died in Baden-Baden, Germany at the age of 66.

Robert Koch's contributions to microbiology and bacteriology have had a major impact on modern scientific research practices and the study of infectious diseases. His work helped to establish the germ theory of disease as well as to refute spontaneous generation. Koch's laboratory techniques and sanitation methods serve as the foundation for modern day methods for microbe identification and disease control.

Robert Koch Fast Facts

  • Full Name: Robert Heinrich Hermann Koch
  • Known For: Koch's postulates; Identifying anthrax, tuberculosis, and cholera bacteria; Father of modern bacteriology
  • Born: December 11, 1843 in Clausthal, Germany
  • Parents' Names: Hermann Koch and Mathilde Julie Henriette Biewand
  • Died: May 27, 1910 in Baden-Baden, Germany
  • Education: University of Göttingen, MD degree
  • Published Works: Investigations into the Etiology of Traumatic Infective Diseases (1877)
  • Key Accomplishments: Nobel Prize for Physiology or Medicine (1905)
  • Spouses' Names: Emmy Fraatz (1867–1893), Hedwig Freiberg (1893–1910)
  • Child's Name: Gertrude Koch


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  • "Robert Koch Scientific Works." Robert Koch Institute,
  • Sakula, Alex. "Robert Koch: Centenary of the Discovery of the Tubercle Bacillus, 1882." National Center for Biotechnology Information, U.S. National Library of Medicine, Apr. 1983,