Selection with Antibiotics

Definition

Growth of cells in the presence of an antibiotic is an efficient way to select a small number of cells that contain a plasmid from among a much larger number that do not have the plasmid. Antibiotics kill cells by inhibiting cellular components that are necessary for vital processes. Plasmid cloning vectors generally contain a gene that encodes a factor that makes a cell containing that plasmid resistant to an antibiotic and thus able to grow in its presence. A culture of cells, some of which contain the plasmid, can be spread on an agar plate that contains the antibiotic. Cells that contain the plasmid are able to grow and form a colony on the plate, while cells that do not contain the plasmid are unable to grow.

Discussion

Antibiotics slow the growth of or kill bacteria by inhibiting a variety of cellular processes, including cell wall biosynthesis, protein synthesis, DNA replication, and transcription. The antibiotics used most commonly for recombinant DNA work in E. coli...