This is a Provisional monograph.

Membrane lauryl sulfate broth (MLSB) was modified by Sartory and Howard (1992) by the addition of agar, sodium pyruvate to assist the recovery of stressed organisms and 5-bromo-4-chloro-3-indolyl-β-D-glucuronide (BCIG) either as the sodium or the cyclohexylammonium salt for the indication of the production of β-glucuronidase by Escherichia coli. The medium has two advantages over MLSB: (i) only one membrane is used for the test and this is incubated at 37°C; (ii) coliforms are yellow and Escherichia coli colonies are typically green. Details of the method can be found in Anon. (2002).

Dissolve the ingredients in the water by boiling and adjust the pH such that, after sterilisation, the final pH will be 7.4. In practice, the adjusted pH should be between 7.6 and 7.7. Dispense in suitable volumes and sterilise by autoclaving at 121°C for 15 min. The sodium salt of BCIG will dissolve in water. The cyclohexylammonium salt is dissolved in 3 mL of a solution consisting of 2.5 mL of 95% v/v aqueous ethanol and 0.5 mL of 1 M sodium hydroxide.