Blue-white screening

Blue-white screening is a laboratory technique used to identify bacteria that have successfully incorporated a specific piece of DNA, like a gene insert. Scientists insert this DNA into bacteria and grow them on special plates containing a substance called X-gal, which turns blue when bacteria produce a certain enzyme. If the bacteria take up the DNA with the gene insert, the enzyme isn’t produced, so the colonies stay white. If they don't take up the insert, the bacteria produce the enzyme and turn blue. Thus, white colonies indicate successful DNA insertion, simplifying the identification process.