See beta-galactosidase assay for other methods.
This method uses 4-Methylumbelliferyl beta-D-galactopyranoside (MUG) for lacZ detection (Sigma M1633). MUG has the advantage that it gets into the cell. MUG can be detected via fluorescence using 360nm/460nm
- 2 mg/ml MUG in DMSO. Use as 10x (final concentration 200 μg/ml)
- It works to grow liquid cultures with MUG. The fluorescence is easily detected on a normal UV box (cells look blue)
- The MUG can be directly substituted for ONPG in a Miller-type assay
- It is highly amenable to reading on a plate reader in 96-well format
- Vidal-Aroca F, Giannattasio M, Brunelli E, Vezzoli A, Plevani P, Muzi-Falconi M, and Bertoni G. One-step high-throughput assay for quantitative detection of beta-galactosidase activity in intact gram-negative bacteria, yeast, and mammalian cells. Biotechniques. 2006 Apr;40(4):433-4, 436, 438 passim.