. Dry media plates in a laminar flow hood.
2. Add 40 µl 100mM IPTG and 120 µl X-Gal (20 mg/ml) to the surface of each plate and spread over
entire surface.
Note: The edges of the plate are difficult to spread adequately and may give false positives. We advise
picking colonies in the middle of the plate, if possible, for best results.
3. Dry X-Gal/IPTG-coated media in a laminar flow hood for approximately 30 minutes before use.
4. Spread transformed competent cells as desired.