For selective enumeration of presumptive Escherichia coli and other coliforms from milk products. MUG LAURYL SULPHATE BROTH, MODIFIED (as per ISO)is usedfor the selectiveand enumeration and presumptive enumeration of Escherichia coli. Sodium Lauryl sulphate broth promotes a rich growth and copious gas production from small inocula of coliform organisms. Aerobic sporing bacteria are completely inhibited.Tryptoneprovides the nitrogen, carbon compounds, vitamins and amino acids. The addition of MUG to the medium allows the positive discrimination of E. colistrains. As themajority of E. coliproduces the β-glucuronidase enzyme, they are able to hydrolyse MUG, releasing a fluorogenic compound. Tryptophan acts as a substrate for the indole test.Lactose is the fermentable sugar. Sodium chloride maintains the osmotic balance of the medium.Dipotassium phosphateand Mono potassium phosphate controls the pH during fermentation of Lactose. Lactose-positive bacteria metabolize lactose with gas formationis indicated by using inverted Durham tubes. Incubate at the wished temperature for 24 hours. In case of gas formation the Durham tubes rise or/and show bubbles. Turbidity of the medium accompanied by formation of gas within 48 hours is a positive presumptive test for the presence of E. coli and/or other coliform organisms. Prepared Broth becomescloudy if stored at 2-8°C, but it should get cleared at room temperature. If there is fermentation in the tube incubated at 44°C after 8 to 24 hours, perform indole test by adding Kovac‘s reagent (TR 008). A positive indole test in a broth tube showing gas production at 44°C indicates the presence of Escherichia coli. If no fermentation occurs in the tube incubated at 30°C after 24 hours, the primary fermentation is assumed to be due to organisms other than coliforms.