MUG Lauryl Sulphate Broth, 5 kg

Lauryl Sulphate Broth was formulated by Mallmann and Darby (1) and is recommended by APHA for the detection and enumeration of coliform organisms in foods, water and wastewater (2, 3). MUG is added in Lauryl Sulphate Broth as the fluorogenic compound which permits the rapid detection of Escherichia coli when observed under UV light where further confirmation is not required (2, 4). MUG detects anaerogenic strains which may not be detected in the conventional procedure. Feng and Hartman (5) used MUG-containing medium for studying ß-glucuronidase activity and found Escherichia coli has 96-100% activity, Salmonella species with 17% and Shigella species 40% activity and other genera were negative. For weakly positive strains incubation should be carried out overnight. Robison (4) reported no false negative results and about 5% false positive results. Casein enzymic hydrolysate provides nutrients while lactose act as energy source. Sodium lauryl sulphate inhibits many organisms other than coliforms. 4-methylumbelliferyl-ß-D-glucuronide is hydrolyzed by an enzyme ß-glucuronidase possessed by organisms to yield 4-methylumbelliferone, a fluorescent end product. Inoculate 10 ml of the test specimen into three tubes each of single strength and double strength medium. Incubate the tubes at 35°C for 24 hours. Observe for opacity and gas formation. For confirmation of presumptive E. coli , observe for fluorescence and perform indole reaction using Kovacs Reagent (R008). Storage and Shelf-life: Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label. References: 1. Mallmann and Darby, 1941, Am.J. Public Health, 31:127. 2. Downes F. P and Ito K. (Ed.), 2001 Compendium of Methods for the Microbiological Examination of Foods, 3rd ed., APHA, Washington, D.C. 3. Greenberg A. E., Trussell R. R. and Clesceri L. S. (Eds.), 1985, Standard Methods for the Examination of Water and Wastewater, 16th ed., APHA, Washington, D.C. 4. Robison, 1984, Appl.Environ.Microbiol., 48:285. 5. Feng P.C.S. and Hartman P. A., 1982, Appl. Environ. Microbiol., 43:1320.