Index >> Bacterial Recombination >> Unidirectional Genetic Transfer

Davis (1950) repeated the experiment by using a U-shaped tube, each arm of which contained one auxotrophic strain. The two arms of the V-tube were separated by a sintered glass filter which permitted the passage of the nutrient medium and particles smaller than 0.1 µ, but was impervious to E coli cells. The culture medium was made to pass through the filter from one arm to the other by alternating suction and pressure. In this experimental setup the two auxotrophic strains shared the same growth medium, but did not come into contact with each other. No prototrophs appeared in either arm of the V-tube, proving that contact between the two conjugating parent cells was essential for the formation of recombinant bacterial genomes.