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Rediscover STEAM

Esther Lederberg, Microbiologist & Pioneer in Bacterial Genetics

Esther Lederberg was born in the Bronx, New York to David Zimmer and Pauline Geller Zimmer. Her father, who grew up in the Austrio-Hungarian empire, immigrated to the United States, where he ran a print shop. Growing up during the Great Depression, the Zimmer family struggled to make ends meet.

Lederberg attended Evander Child’s High School in the Bronx and continued onto Hunter College through a scholarship, originally intending to major in either French or Literature. However, she opted for biochemistry, spurning the advice of her teachers, who believed that women could not succeed in science. She served as a research assistant under Bernard Ogilvie Doge, a plant pathologist at New York Botanical Garden; there, she began working on her undergraduate thesis. Lederberg then worked at the Carnegie Institute of Washington as a teaching assistant in order to pay for her studies. There, she wrote her first research paper on genetics, tackling the effect of ultraviolet radiation and x-rays on mutation production in Penicillium notatum. Because of her financial situation, she had to eat frog’s legs that were left over from dissections.

In 1944, Lederberg won a fellowship and then began pursuing a Master’s degree in genetics at Stanford University. During her time at Stanford, she met Joshua Lederberg, a pioneer in the world’s understanding of microbial genetics, and five months later, she married him. She followed him to the University of Wisconsin, where he had received a job as a professor. While completing her Ph.D., she observed abnormal patterns in different colonies of the bacteria E. coli, eventually discovering phage lambda in 1950. She realized that the virus did not kill the host but instead merged with the host’s DNA. This allowed its genome to be transferred from one generation to another with no effect on the host. ‘Phage therapy’ is also being used to treat bacterial infection in light of the growing antibiotic resistance of bacteria. Lederberg’s findings have been vital for successive breakthroughs in modern biology, such as the discoveries of recombinant DNA, constructing cloning vectors, and gene regulation.

At the same time, Lederberg worked with her husband to understand how bacteria quickly evolve to become resistant to a drug that previously killed them. They discovered that chromosome changes could actually be traced in a laboratory, which revealed bacteria’s ability to rapidly mutate. In 1953, Joshua Lederberg received an award from Eli Lilly for their work, and while he tried to argue that Lederberg deserved it as much as he did, she modestly downplayed her involvement and refused to take credit for her contribution.

A year later, Esther Lederberg developed a technique known as “replica plating,” which enables scientists to replicate whole colonies of cultures on a series of agar plates with an identical spatial configuration. This allowed her and Joshua Lederberg to isolate bacterial mutations and verify that they existed in the original culture. Thus, in 1956, the two were awarded the Pastor Award by the Society of Illinois Bacteriologists. Two years later, all of Lederberg’s achievements were dwarfed by Joshua Lederberg winning the Nobel Prize. However, much of the experimental work and research that won him the Nobel Prize was actually performed by Esther Lederberg herself.

In 1959, the couple returned to Stanford, and Joshua Lederberg founded the Department of Genetics while Esther Lederberg received the post of an untenured research associate professor in the Department of Microbiology and Immunology. In 1966, the two got divorced, and Esther Lederberg continued not to receive any recognition at the university. Fifteen years later, she joined the faculty at Stanford, and her title was changed from Senior Scientist to Adjunct Professor. This change was a demotion as her contract needed to be renewed on a regular basis and was dependent on her obtaining research grants. Finally, in 1976, she received the respect she deserved and was appointed the Director of Stanford’s Plasmid Reference Center. Lederberg was key in naming numerous plasmids and the genes that they contained. Even after she stepped down from Director in 1985, she continued to work at the lab.

In 1989, she met her second husband, Matthew Simon and married him 4 years later. On November 11, 2006, Lederberg passed away from pneumonia. Her legacy as one of the most influential contributors to modern genetic technologies and research lives on forever. Her teachers were correct in thinking a woman would struggle to succeed in the biochemistry field, which is rampant with sexism; however, they underestimated Lederberg’s academic persistence, and unshakable determination. Now, Esther Ledeberg is revered as both an incredible scientist and a remarkable woman.

by Raina Talwar Bhatia


Marks, L. (2015, December). Professor Esther Lederberg | Biographical summary.

Nakonechny, W. (2016, December). Invisible Esther: The ‘other’ Lederberg. The Jackson Laboratory.

Piqueras, M. (2014, July). Esther Lederberg, Pioneer of Bacterial Genetics. Retrieved from Small Things Considered:

Magazine, S. (2007). Microbiology pioneer. Stanford Magazine.



Rediscover STEAM sheds light on the often overlooked and untold stories of gender minorities in STEM and the arts throughout history to increase representation and bridge the gender gap. We aim to rewrite false narratives and share stories from a diverse set of backgrounds.

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