A seminal discovery of modern biology was Joshua Lederberg’s demonstration that bacteria can swap genes through a process known as bacterial recombination. Not only is recombination the mechanism by which antibiotic resistance genes are transferred, but it’s also been turned into a useful tool for genetically manipulating E. coli, which has led to so many things, including the industrial synthesis of insulin; it’s also a key tool–and at one time–the key tool for molecular genetics.
So while working my way through Population Genetics of Bacteria: A Tribute to Thomas S. Whittam, I came across this fascinating footnote in a chapter by microbiologist and population geneticist Bruce Levin about Lederberg’s key discovery (italics mine):
Joshua Lederberg also knew how rare recombination is in E. coli. Had he worked with any of the other then prominent laboratory strains…or almost any wild strain, he would have gotten negative results in his 1946 experiments testing for recombination in this bacterium. The strain he used, E. coli K-12, was an oddball. It bore a plasmid, F, which was permanently derepressed for conjugative pili synthesis and a chromosome with insertion sequences homologous to those on the plasmid which enabled this conjugation-encoding accessory element to integrate into the chromosome by Rec-mediated recombination. I once asked Josh how many other strains he would have looked at if he had gotten negative results with K-12. He told me, “One.” Lederberg and Tatum’s preparation to do these experiments, generating the amino acid and fermentation negative mutants, was a considerable task at the time. What a combination: serendipity and a prepared, brilliant mind!
I have the impression that people who aren’t scientists often think there is this huge implacable juggernaut that will inevitably discover what needs to be discovered. But so many key discoveries are actually very serendipitous.