Horizontal gene transfer
Zinder and Lederberg · 1951
Bacteria can pick up genes from other cells by transformation, transduction or conjugation, not only by inheriting them. Lederberg and Zinder showed in 1951 that a virus could carry genes from one strain of Salmonella to another, and Lederberg's earlier work with Edward Tatum showed that E. coli can exchange genes by conjugation. The material treats the process as the main route by which antibiotic resistance spreads among bacteria.