 In 1946 , Joshua Lederberg and Edward Tatum first described the phenomenon known as bacterial conjugation using E. coli as a model bacterium , and it remains the primary model to study conjugation . E. coli was an integral part of the first experiments to understand phage genetics , and early researchers , such as Seymour <unk> , used E. coli and phage T4 to understand the topography of gene structure . Prior to <unk> 's research , it was not known whether the gene was a linear structure , or if it had a branching pattern . 
