This screening is to select colonies expressing a functional Beta-galactosidase protein (lacZ gene). They appear as blue colonies on agar plates.
- Pre-warm an LB agar plate at 37degC.
- For each plate, mix 20 ul of X-Gal (40 mg/ml dissolved in DMF), 20 ul of IPTG (200 mM, ReadyMade stock) and 160 ul of sterile LB.
- Spread evenly on the plate near the flame.
- Incubate it at 37degC until dry and use.
SAFETY NOTE: DMF is toxic, always use gloves and a face mask.