Details for amaxa FAQ article #252

«Should I transfect circular or linear plasmid DNA to obtain stable transfectants?»

Stable transfectants can be obtained from circular as well as linearized plasmid. However, we recommend linearizing the plasmid with a suitable restriction enzyme for the following reason:
a circular plasmid will recombine into the genome at a random position within the plasmid. Therefore there is a relatively high likelihood that the expression cassette for your gene of interest will be destroyed, leading to antibiotic resistant clones that do not express the GOI. By linearizing the plasmid you can determine at which position within the plasmid the recombination occurs thereby conserving the expression cassette in most cases.