LST-MUG Broth for Pathogenic Escherichia coli Identification (Including O157:H7/NM)
LST-MUG Broth is a selective medium applied for the identification test of pathogenic Escherichia coli, covering O157:H7 and O157:H7/NM strains. It combines lactose fermentation and MUG fluorescence reaction to distinguish typical E. coli from O157:H7 pathogenic strains.
Formula Composition (per Liter)
| Ingredient |
Content |
| Tryptone |
20.0 g |
| Sodium chloride |
5.0 g |
| Lactose |
5.0 g |
| Dipotassium hydrogen phosphate |
2.75 g |
| Potassium dihydrogen phosphate |
2.75 g |
| Sodium lauryl sulfate |
0.1 g |
| MUG (4-methylumbelliferyl-β-D-glucuronide) |
0.1 g |
| Final pH |
6.8 ± 0.2 |
Test Principle
Tryptone provides carbon and nitrogen sources to support bacterial growth. Sodium chloride maintains proper osmotic balance. Lactose serves as fermentable carbohydrate for coliform group. Dipotassium hydrogen phosphate and potassium dihydrogen phosphate act as buffering agents. Sodium lauryl sulfate inhibits non-coliform bacteria.
Glucuronidase produced by most E. coli hydrolyzes the β-glucuronide bond of MUG. The liberated 4-methylumbelliferone emits blue-white fluorescence under 366 nm ultraviolet light. Approximately 97% of general E. coli, 10% of Salmonella and a small number of Shigella strains carry glucuronidase activity. Pathogenic E. coli (including O157:H7) do not produce glucuronidase, so no fluorescence can be observed.
Directions for Use
Take one sachet of the product, add into 50 mL distilled or deionized water, stir and heat to boiling for full dissolution. Dispense into test tubes with small inverted Durham tubes. Autoclave at 121 ℃ for 15 minutes, cool to room temperature for later use.
Quality Control
Inoculate specified quality control strains into the prepared medium, incubate at 44.5 ℃ ± 0.5 ℃ for 24 hours and observe the reaction results.
