Genetic Recombination in Bacteria: A Discovery Account

For the past four decades, bacteria have been favored objects for molecular genetic research. Along with bacteriophages and other plasmids, they have also been instrumental in the contemporary revolution in biotechnology. The importance of bacteria as agents of infectious disease was clearly established by 1876, but this motivated little interest in their fundamental biology until about sixty-five years later. For most of that interval, the genetics of bacteria was a particularly neglected no-man’s-land between the disciplines of genetics and of medical bacteriology. Bacteria could not be adopted as models for genetic research until there was some substantiation of the view that they had a genetic system like other organisms. On the contrary, Julian Huxley had once suggested of bacteria that “the entire organism appears to function both as soma and germ plasm and evolution must be a matter of alteration in the reaction system as a whole” (34). Other influential figures like Hinshelwood (32) and Darlington (15) voiced similar views. (Darlington and Huxley, but not Hinshelwood. quickly embraced a more modem perspective when new evidence emerged.) The question reached closure in 1946 with the demonstration of sexual crossing in the bacterium Escherichia coli strain K-12 (66). A brief reminiscence has been published for the fortieth anniversary of that publication (60). That article was joined with some reflections on whether this was a postmature discovery and whether the same inquiry might have been made at a much earlier historical epoch, perhaps promptly after the rediscovery of Mendelism at the turn of the century (103). The present account concentrates on the scientific milieu and convergent personal histories of Francis J. Ryan (19161963) (76, 80), Edward L. Tatum (1909-1975) (59, 611, and myself, Joshua Lederberg (1925) at Columbia