Insertional inactivation technique of recombinant DNA technology used to select bacteria that carry recombinant plasmids; a fragment of foreign DNA is inserted into a restriction site within a gene for antibiotic resistance, thus causing that gene to become nonfunctional.  It is often used to identify recombinant vectors in gene cloning and in turn to distinguish a recombinant vector from a non-recombinant vector. For example, insertion of a piece of foreign DNA into a cloning site which is located on an antibiotic-resistant gene on the vector can lead to loss of the antibiotic resistance phenotype by insertional inactivation. The recombinant vector will, therefore, specify antibiotic sensitivity, whilst the non-recombinant vector will specify antibiotic resistance.