This medium complies with the APHA Recommendations for Water Examination (1998) and the ISO 5541-2 (1996) for milk and milk products.
Mode of Action
The high nutrient quality and the presence of phosphate buffer in this medium ensure rapid growth and increased gas production of even “slowly lactose-fermenting” colifirm bacteria. Gas formation can be detected by using fermentation tubes. The lauryl sulfate largely inhibits the growth of undesired bacteria.
Typical Composition (g/litre)
Tryptose 20.0; lactose 5.0; sodium chloride 5.0; sodium lauryl sulfate 0.1; di-potassium hydrogen phoshate 2.75; potassium dihydrogen phosphate 2.75.
Suspend 35.6 g/litre or more, dispense into test tubes fitted with DURHAM tubes, autoclave (15 min at 121 °C).
pH: 6.8 ± 0.2 at 25 °C.
The prepared broth is clear and yellowish-brown.
Incubation: up to 48 h at 35 °C (or 30 °C) aerobically.
American Public Health Association, American Water Works Association and Water Pollution Control Federation: Standard Methods for the Examination of Water and Wastewater, 20th ed., Washington, 1998.
HAJNA, A.A., a. PERRY, C.A. Comparative study of presumptive and confirmative media for bacteria of the coliform group and for fecal Streptococci. – Am. J. Publ. Health , 33; 550-556 (1943).
MALLMANN, W.L., a. DARBY, C.W.: Use of a lauryl sulfate tryptose broth for the detection of coliform organisms. – Am. J. Publ. Health, 31; 127-134
International Standardization Organization: Milk and milk products – Enumeration of coliforms. Part 2: Most probable number technique at 30 °C. ISO/CD 5541-2 (1996).