Hybridization techniques are widely used to identify recombinants. This is based on the ability of nucleic acids hybridize with complementary DNA. The transformed cells are transferred on to a nitrocellulose membrane which is subjected to cell lysis. The double stranded DNA is converted to single stranded DNA and immobilized on the membrane. Then it is treated with radiolabelled probes complementary to target DNA. If the desired DNA is present, the probes will be hybridized which can be detected by autoradiography.
Apart from these methods, immunochemical methods are used to detect protein products to screen