Joshua Lederberg

Joshua Lederberg


With Tatum he published "Gene Recombination in Escherichia coli" (1946), in which he reported that the mixing of two different strains of a bacterium resulted in genetic recombination between them and thus to a new, crossbred strain of the bacterium. Scientists had previously thought that bacteria only reproduced asexually--i.e., by cells splitting in two; Lederberg and Tatum showed that they could also reproduce sexually, and that bacterial genetic systems are similar to those of multicellular organisms.

While biologists who had not previously believed that "sex" existed in bacteria such as E. coli were still confirming Lederberg's discovery, he and his student Norton D. Zinder reported another and equally surprising finding. In the paper "Genetic Exchange in Salmonella" (1952), they revealed that certain bacteriophages (bacteria-infecting viruses) were capable of carrying a bacterial gene from one bacterium to another, a phenomenon they termed transduction.

