Final answer:
Replica plating is a microbiological technique used for the identification of specific bacterial colonies or mutants by transferring them from a master plate to secondary plates with different nutrient compositions, including a nutritionally complete control plate, to observe their growth.
Step-by-step explanation:
The process described for identifying a specific colony by copying a plate is known as replica plating. This microbiological technique is important for isolating and identifying bacterial mutants, especially those with nutritional requirements that differ from the wild-type strain, known as auxotrophs. During the replica plating process, a master plate containing bacterial colonies is pressed onto sterile velvet or a similar material, which then transfers an imprint of these colonies onto other agar plates with different nutrient compositions. By comparing the growth of colonies on nutrient-deficient media with that on a nutritionally complete medium, researchers can determine which bacteria are auxotrophs and require specific nutrients for growth. This method allows for the identification and further study of different bacterial clones and mutants present within a mixed culture without disturbing the original plate.
Cells are plated on a nutritionally complete plate in addition to nutrient-deficient plates during replica plating in order to ensure that each bacterial colony is successfully transferred and can grow if provided with adequate nutrients. This serves as a control to verify the transfer process and to distinguish between mutant and non-mutant strains based on their ability to grow without the specific nutrient being tested.