Discovery of sexual processes in the reproduction of bacteria.

In 1958 Lederberg shared the Nobel Prize in Physiology or Medicine with Tatum and Beadle (No. 254.3) "for his discoveries concerning genetic recombination and the organization of the genetic material of bacteria."

Description of a new mechanism (“transduction”) for the transfer of genetic characters from one bacterial strain to another.

Demonstration of the mutational basis of antibiotic resistance. Digital facsimile from PubMedCentral at this link.

Working as a graduate student with Lederberg, Zinder discovered that a bacteriophage can carry genes from one bacterium to another. Initial experiments were carried out using Salmonella. Zinder and Lederberg named this process of genetic exchange transduction. Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector. It is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome. Digital facsimile from PubMedCentral at this link.

DENDRAL is considered the first expert system because it automated the decision-making process and problem-solving behavior of organic chemists. The project consisted of research on two main programs, Heuristic Dendral and Meta-Dendral,^[4] and several sub-programs. It was written in Lisp (programming language). Digital facsimile from the National Library of Medicine at this link.

Valuable for its detailed, but highly compressed discussion of the earliest history of these subjects, co-authored by Lederberg, who played a significant role during that period.