Tonya G. answered • 01/17/20
Tonya G. Experienced Science Teacher and Tutor
I am not sure exactly what you are looking for as the answer because there are several different methods. Normally when we screen for bacteria it is because we are looking for that certain strain. We can do a positive-selection system which means that if the positive vector can conditionally(depending on the environment) express a lethal gene like for example, a restriction enzyme that digests the genomic DNA of the bacterial host, if the DNA is successfully inserted in the plasmid, that lethal gene will no longer be expressed. As a result, only cells with recombinant plasmids are able to grow. This approach save a lot time and money because the success rate of producing only the recombinant plasmids is greater than 99%.
