Max Delbrück

Max Delbrück (1906-1981), German-born American biologist and winner of the 1969 Nobel Prize in physiology or medicine, which he shared with fellow Americans Salvador E. Luria and Alfred D. Hershey for their discoveries concerning the replication mechanism of viruses and their genetic structure. Using the bacteriophage, a simple virus that infects bacteria, the trio established the field of bacterial genetics and helped lay the foundation for modern molecular biology.

Delbrück was born in Berlin, Germany, on September 4, 1906. He studied at several German universities before graduating from the University of Göttingen with a Ph.D. degree in physics in 1930. He then pursued postdoctoral work at the University of Bristol in England, at the University of Copenhagen in Denmark, and at the University of Zürich in Switzerland. From 1932 to 1937 Delbrück was a researcher at the Kaiser Wilhelm Institute for Chemistry in Berlin. It was during these years that his interests shifted to biological research. In 1937 he received a fellowship to study genetics at the California Institute of Technology (Caltech) in Pasadena. It was during this time that he became interested in the bacteriophage. In 1940 he became an instructor in physics at Vanderbilt University in Nashville, Tennessee, and began his collaboration with Luria and Hershey. The three of them organized the Phage group which, through their meetings at Cold Spring Harbor Laboratory on Long Island, New York, studied the genetics of the bacteriophage. In 1947, Delbrück returned to Caltech as a professor of biology. From 1961 to 1963 he helped establish the Institute of Genetics at the University of Cologne in Germany. He retired from Caltech in 1977 and joined the institute's board of trustees.

In the 1930s genes were known to be responsible for giving one generation characteristics of its parent. However, the physical structure of genes and how they transmitted genetic information, was not understood. Delbrück believed that genes were molecules whose chemical structure could be precisely analyzed. In the late 1930s at Caltech, Delbrück began studying bacteriophages because he thought virus replication was related to genetic replication. In 1943 he and Luria determined that spontaneous genetic mutations were responsible for the ability of some bacteria to resist the destructive action of particular bacteriophages. Three years later, Delbrück and Hershey independently discovered that bacteriophages could exchange genetic material to produce offspring with different infective capabilities than either parent. This was the first example of deoxyribonucleic acid (DNA) recombination in viruses. In 1952 Hershey and geneticist Martha Chase at Cold Spring Harbor Laboratory proved that genes were made of DNA, and one year later American geneticist James D. Watson and British biophysicist Francis Crick revealed the double-helix structure of DNA and suggested how genetic information was actually transmitted.