Replica plating Technique: Isolation of Mutants FIGURE 7.2 (a) Replica plating method for detection of nutritional mu- tants. (b) Nutritional mutants, as re- vealed by the replica plating method The left photo shows the master plate The colonies not appearing on the epoca plate are marked with an x. The replica plate lacked one nutrient leucine) present in the master plate Penicillin-Selection method Penicillin kills only growing cells. If penicillin is added to a population growing in a medium lacking the growth factor required by the designed mutant, the parent cells will be killed whereas the non-growing mutant cells will be unaffectedReplica Plating Technique: Isolation of Mutants • Penicillin-Selection Method – Penicillin kills only growing cells. If penicillin is added to a population growing in a medium lacking the growth factor required by the designed mutant, the parent cells will be killed, whereas the non-growing mutant cells will be unaffected