[1] Lauryl tryptose broth is used for the most probable number test of coliforms in waters, effluent or sewage.
It acts as a confirmation test for lactose fermentation with gas production.
Formula in grams/litre (g/L) Samples positive for gas production are transferred to brilliant green lactose bile broth (BLGB) to detect the ability to grow in the presence of bile and produce gas at 95 °F (35 °C) for 48 hours.
The absence of gas production in 48 hours is considered a negative test for coliforms.
[2] Gas production serves as both a presumptive test and a confirmatory medium.