Lauryl tryptose broth (LTB) is a selective growth medium (broth) for coliforms.
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. Sodium lauryl sulfate inhibits organisms other than coliforms.
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 ðF (35 ðC) for 48 hours. The absence of gas production in 48 hours is considered a negative test for coliforms. Gas production serves as both a presumptive test and a confirmatory medium.
Fecal coliforms are distinguished from coliforms by growth in EC broth at 113.9 ðF (45.5 ðC) for 24 hours.