Joshua Lederberg and Edward L. Tatum publish the first paper on a type of bacterial mating called conjugation. The proof is based on the generation of daughter cells able to grow in media that cannot support growth of either of the parent cells. Their experiments showed that this type of gene exchange requires direct contact between bacteria. At the time Lederberg began studying with Tatum, scientists believed that bacteria reproduced asexually, but from the work of Beadle and Tatum, Lederberg knew that fungi reproduced sexually and he suspected that bacteria did as well.
Lederberg and Tatum Discover Bacterial Mating and Phage Recombination