Selection of Recombinant Clones - After the multiplication of bacteria with inserts, we get a huge number of clones, which contain inserts of use or interest. In addition, a variety of unpredictable and aberrant recombination can occur, including vectors that have incorporated two or more inserts, and recombination in which the inserts have been altered by recombination within the host cell.

Thus transformation and multiplication of clone does not mark the end of gene cloning. It is just one of the steps in recombinant technology. The task of isolating a desired recombinant from a population of bacteria depends very much upon the cloning strategy that has been adopted and type of vector that has been used.

Various methods such as genetic and immunochemical methods, south-western blotting, nucleic acid hybridization and recombination methods are available. But nucleic acid hybridization with labelled probes is most generally applicable.