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Thermo Scientific™ MUG Disk

Reagent-impregnated disk recommended for use in rapid, presumptive identification of Escherichia coli.

Supplier:  Thermo Scientific™ R21135

Catalog No. R21135

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Presumptively identify Escherichia coli by fluorogenic assay procedure using Thermo Scientific™ Remel™ MUG Disk. In 1976, Kilian and Bulow reported the enzyme β-glucuronidase is present in most strains of E. coli (97%)1. The substrate, 4-methylumbelliferyl- β-D-glucuronide (MUG), is found to be both sensitive and selective for detection of β-glucuronidase activity. Trepeta and Edberg used the MUG test in conjunction with oxidase, indole, and lactose fermentation for rapid, cost effective identification of E. coli2.

Godsey et al. supported their findings in an evaluation of methods based on microbial enzyme activity profiles3. Most strains of E. coli produce an enzyme β-D-glucuronidase. In the indole test, the enzyme tryptophanase attacks tryptophan molecule on its side chain, leaving the aromatic ring in the form of indole. The indole is then detected by addition of ρ-dimethylamino-benzaldehyde (Kavocs’ Reagent) which produces a red color. β-D-glucuronidase is an enzyme that cleaves the substrate 4-methylumbelliferyl-β-D-glucuronide (MUG) and thereby produces a fluorescent product called methylumbelliferone4. This compound is detectable using a long wave ultraviolet light (360 nm).

  • Ready to use - 4-methylumbelliferyl- β-D-glucuronide-impregnated disk
  • Easy to store - No special storage required
  • Easy to interpret - With visual inspection
    • In MUG Disk test, examine the disk for fluorescence using a longwave ultraviolet light (360nm) in a darkened room. Blue fluorescence is interpreted as positive test.
    • In Indole test, add one drop of Kovacs‘ Indole Reagent to the disk and immediately observe for red color development.


MUG Disk Test (Direct or Tube Test):

Positive test - Blue fluorescence observed under 360 nm UV light

Negative test - No fluorescence observed under 360 nm UV light

Indole Test:

Positive test - Red color development on the disk or in the tube

Negative test - No red color development on the disk or in the tube



E. coli
E. coli Testing Kit
25 Disks/Pk.


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