Following the Lederberg experiment, a scientist plated E.

Last updated: 7/31/2022

Following the Lederberg experiment, a scientist plated E. coli cells onto an agar plate with rich media and 125 colonies grew on this master plate. The scientist then replica printed the 125 colonies from the master plate onto two agar plates containing rich media plus the antibiotic kanamycin, which is known to kill E. coli cells. After an overnight incubation, the scientist observed a few antibiotic resistant mutant colonies growing on the same spots when comparing the two replica plates. What would explain these results? Some cells acquired antibiotic resistant mutations after they were grown in the presence of the antibiotic. All of the 125 colonies were antibiotic resistant before they were grown in the presence of the antibiotic. Some resistant mutants were present within the population of 125 colonies before they were grown in the presence of the antibiotic.