Describe the procedure involved in Blue-White colony selection methods.

Explanation

Blue-White Colony Selection Method is a powerful method used for screening of recombinant plasmid . In this method, a reporter gene lacZ is inserted in the vector . The lacZ encodes the enzyme
`beta` galactosidase breaks a synthetic substrates called X - gal ( 5 - bromo - 4 chloroindolyl- `beta` - D- galacto - pyranoside ) into an insoluble blue coloured product . If a foreign gene is inserted into lacZ m this gene will be inactivated . Therefore , no - blue colour will develop (white ) because `beta` - galactosidase is not synthesized due to inactivation of lacZ. Therefore , the host cell containing r - DNA form white coloured colonies on the medium contain Z - gal , whereas the other cells containing non - recombinant DNNA will develop the blue coloured colonies On the basis of colony colour , the recombinants can be selected .