Lauryl Sulfate Broth was formulated by Mallmann and Darby for detection of coliform bacteria in water. This is a selective medium because it contains sodium lauryl sulfate which inhibits Gram positive microorganisms. Lactose is added to detect rapid lactose fermentation by coliforms. The addition of 4- methylumbelliferyl-B-D-glucuronide (MUG) to Lauryl Sulfate Broth allows for the rapid detection (4-24 hours) of E. coli-When the incubated medium is observed for fluorescence using a long-wave UV light (365 nm) source. It can also detect anaerogenic E-coli strains. Most strains of E. coli produce B- glucuronidase which hydrolyzes MUG to the fluorogenic compound 4- methyl-umbelliferone. Studies by Feng and Hartman noted that most E coli strains (96%) and all enterotoxigenic E coli strains (100%) and a moderate number of Salmonella (17%) and Shigella (40%) stains produce B-glucuronidase. False positives can also be caused by Streptococcus sp.

Expected cultural response after 18-24 hours at 35.0°C.

Organism Result Escherichia coli ATCC 25922 Growth, Gas +, Fluorescence + Proteus mirabilis ATCC 12453 Growth, Gas -, Fluorescence - Staphylococcus aureus ATCC 25923 No Growth

Appearance: White to off-white crystalline powder Solubility: Clear, light amber and complete pH: 6.8± 0.2

Directions per Liter Dissolve 35.56 grams per liter of distilled/deionized (DDI) water, heating with stirring until completely solubilized, adjusting pH as necessary. Dispense into appropriate containers, loosen caps and autoclave for 15 minutes at 121ºC (15psi).

Storage Store at 0-5ºC (store unopened media at 2-30°C). Opened bottles should be capped tightly and kept in a dark, low humidity environment.