Esther Lederberg

Esther Lederberg (1922–2006) was an American microbiologist whose work in bacterial genetics included discovering bacteriophage lambda and developing replica plating.

Joshua Lederberg: An American molecular biologist who studied bacterial genetics and shared the 1958 Nobel Prize in Physiology or Medicine. Her husband and research collaborator, he shared credit for discoveries made in their laboratory.
Replica plating: A method that transfers the spatial pattern of colonies from one microbial culture plate to another. Lederberg developed this method with Joshua Lederberg to identify inherited bacterial traits.
Fluctuation test: An experiment comparing mutation frequencies across independent microbial cultures to distinguish spontaneous mutation from induced change. Replica plating helped demonstrate that resistant bacterial variants can arise before selection.
Operon model: A model in which related bacterial genes are regulated together through shared control sequences. The study of lambda and bacterial gene regulation contributed to the research context in which this model emerged.
Edward Tatum: An American geneticist who helped establish that genes control specific biochemical reactions. He supervised Lederberg’s doctoral research at Stanford University.
Bacteriophage lambda: A virus that infects Escherichia coli and can reproduce either by lysis or by integrating into its host genome. Lederberg discovered this phage and studied its unusual relationship with bacterial cells.
Bacterial genetics: The study of heredity, gene expression, and genetic exchange in bacteria. This field encompasses the experimental problems her research helped make tractable.
Molecular biology: The study of biological processes through the interactions of molecules, especially DNA, RNA, and proteins. Her work connected microbial experiments to fundamental questions about genes and their behavior.
George W. Beadle: An American geneticist whose work with Edward Tatum linked genes to biochemical functions. Lederberg’s doctoral work grew from the research program he and Tatum established.
Bacterial conjugation: The transfer of DNA between bacterial cells through direct contact, commonly mediated by a plasmid. Lederberg’s early research helped establish that bacteria can exchange genetic material.

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