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TBX Agar (AS-1427) | Chromogenic E. coli Enumeration
$105.00 AUD
AuSaMicS Life Science • Chromogenic Media
TBX Agar (Tryptone Bile X-glucuronide Agar)
Chromogenic Medium for Rapid Detection of Escherichia coli (ISO 16649)
TBX Agar is a selective chromogenic medium used for the detection and enumeration of Escherichia coli based on β-glucuronidase (GUD) activity. E. coli colonies produce a characteristic blue-green coloration due to hydrolysis of the chromogenic substrate X-glucuronide, enabling rapid and reliable identification.
AS-1427 Chromogenic E. coli Detection ISO 16649
💧 Water testing 🍽️ Food microbiology 🔬 Rapid confirmation
🏆 E. coli Detection Standard
🧫 Blue-green colonies
⚗️ GUD enzymatic detection
📋 COA + SDS available
🔬 ISO-compliant workflows
Key Function
Direct visual detection of E. coli
🔬 Principle of the Medium
TBX Agar contains tryptone as a nutrient source and bile salts to inhibit Gram-positive organisms. The key component is X-glucuronide, a chromogenic substrate that is cleaved by β-glucuronidase produced by most E. coli strains.
Upon hydrolysis, an insoluble chromophore is released, producing blue-green colonies, allowing direct identification without additional confirmatory tests.
β-glucuronidase (E. coli)
↓
Hydrolysis of X-glucuronide
↓
Blue-green colonies
↓
Hydrolysis of X-glucuronide
↓
Blue-green colonies
🧪 Applications
- Detection and enumeration of E. coli in water
- Food safety testing (dairy, meat, beverages)
- Environmental monitoring
- Membrane filtration and pour plate methods
📊 E. coli Detection Media Comparison
| Medium | Detection Principle | Speed | Best Use |
|---|---|---|---|
| TBX Agar | Chromogenic (GUD) | Fast | ISO E. coli detection |
| MacConkey Agar | Lactose fermentation | Moderate | General coliforms |
| EMB Agar | Dye precipitation | Moderate | Coliform differentiation |
| Chromogenic E. coli Agar | Multiple substrates | Very fast | High-end labs |
💡 Practical Notes
- Most E. coli strains are GUD-positive
- Some strains (e.g. O157:H7) may be GUD-negative
- Incubate typically at 44°C for selective detection
- Provides direct visual confirmation
📋 Technical Specifications
| Product Code | AS-1427 |
| Format | Dehydrated powder |
| Type | Selective chromogenic agar |
| Key Substrate | X-glucuronide |
| Target Enzyme | β-glucuronidase |
| Incubation | ~44°C |
| Storage | 15–25°C dry |
| HS Code | 3821.00.00 |
🧫 Colony Appearance
- 🔵 Blue-green colonies → E. coli
- ⚪ Colourless → non-E. coli
✅ Quality
- ✓ High specificity
- ✓ Clear chromogenic readout
- ✓ COA available
Disclaimer: For laboratory and research use only.