Microbiology and Immunology

Lederberg, Joshua WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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In 1947, while at Yale, Lederberg received an offer from

the University of Wisconsin to become an assistant professor

of genetics. Although only two years away from receiving his

M.D. degree, Lederberg accepted the position at Wisconsin

and received his Ph.D. degree from Yale in 1948. He worked

at the University of Wisconsin for a decade after abandoning

his medical training, although he noted his later honorary

medical degrees from Tufts University and the University of

Turin as being among his most valued.

Lederberg continued to make groundbreaking discover-

ies at Wisconsin that firmly established him as one of the most

promising young intellects in the burgeoning field of genetics.

By perfecting a method to isolate mutant bacteria species

using ultraviolet light, Lederberg was able to prove the long-

held theory that genetic mutationsoccurred spontaneously. He

found he could mate two strains of bacteria, one resistant to

penicillinand the other to streptomycin, and produce bacteria

resistant to both antibiotics. He also found that he could

manipulate a virus’s virulence.

Working with graduate student Norton Zinder,

Lederberg discovered genetic transduction, which involves the

transfer only of hereditary fragments of information between

cells as opposed to complete chromosomal replication (conju-

gation). Lederberg went on to breed unique strains of viruses.

Although these strains promised to reveal much about the

nature of viruses in hopes of one day controlling them, they

also posed a clear threat in terms of creating harmful bio-

chemical substances. At the time, the practical aspect of

Lederberg’s work was hard to evaluate. The Nobel Prize

Committee, however recognized the significance of his contri-

butions to genetics and, in 1958, awarded him the Nobel Prize

in physiology or medicine for the bacterial and viral research

that provided a new line of investigations of viral diseases and

cancer. Lederberg shared the prize with Beadle and Tatum.

Joshua Lederberg (left) who, with his wife Esther (right), discovered the process of bacterial recombination. He was awarded the 1958 Nobel Prize in

Medicine for this and other discoveries.

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