X-Gal

Preparation of a 5-bromo-4-chloro-3-indolyl β-D-galactopyranoside (X-gal) stock solution.
Safety precautions: Harmful if swallowed. Irritating to eyes and skin. Please refer to the material safety data sheet for further information and safety handling practice.

Typically used for blue/white screening via the lac operon. (Often in conjunction with IPTG, but our TOP10 Competent E. coli cells do not require IPTG).

We use X-gal at 50mM (20mg/mL) dissolved into N,N-dimethylformamide (DMF).

• Weigh 200mg X-gal
• Add 10ml DMF
• Mix till dissolved
• Aliquot into these nice blue tubes (1ml/tube)

Usage: Pipette 40μL X-gal directly onto the top of the LB agar plates and spread out with sterile spatula. Wait to dry before usage.