Application

X-Gal is a chromogenic substrate for β-galactosidase that produces a rich blue color that can easily be detected visually over background. X-Gal is the substrate of choice for blue-white selection of recombinant bacterial colonies with the lac⁺ genotype.

5-Bromo-4-chloro-3-indolyl β-D-galactopyranoside has been used in the preparation of X-Gal stock solution to add it in LB agar plates for blue-white screening of transformants.

Biochem/physiol Actions

X-gal is routinely used to detect transgene activity in situ.

General description

5-Bromo-4-chloro-3-indolyl β -D-galactopyranoside, commonly known as X-Gal, is a histochemical substrate for β-galactosidase.

Quantity

Contains 5 mg substrate per tablet

Reconstitution

A stock solution (100 mg/ml) is prepared by dissolving X-Gal in dimethylformamide and should be stored at −20°C and protected from light. Sterilization is not required.