X-Gal (20mg/ml)

X-gal is a chromogenic substrate, used for blue and white spot screening.

IPTG and X-gal combined, are used for blue and white spot screening. IPTG can induce the vector Lac operon DNA segment to synthesize the amino terminal fragment of beta-galactosidase, which can achieve intragenic complementation (alpha complementation) with the defective beta-galactosidase encoded by the host cell. Bacteria that achieve alpha complementation can be formed on X-gal chromogenic substrates to form blue colonies. Insertion of foreign DNA into the multiple cloning site of the plasmid can disrupt alpha complementation and produce white colonies.

This product is a solution of X-gal dissolved in DMF.