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Violet Red Bile Glucose Agar (VRBGA / VRBD) (AS-1376)
$29.00 AUD
AuSaMicS Life Science • Selective Enumeration Agar for Enterobacteriaceae
Violet Red Bile Glucose Agar (VRBGA / VRBD)
Violet Red Bile Glucose Agar is a selective medium for isolation and enumeration of Enterobacteriaceae. It is a modification of MacConkey-type media in which glucose replaces lactose, enabling improved overall recovery of enterobacteria rather than specifically differentiating lactose fermenters.
Cat No.: AS-1376
Enterobacteriaceae AgarVRBG / VRBDAustralian Stock
Format: Dehydrated culture medium Support: COA / technical support available
Application Summary
Professional laboratory use
Reliable workflow integration
Australian stock
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Overview & Applications
Violet Red Bile Glucose Agar is a selective medium for isolation and enumeration of Enterobacteriaceae. It is a modification of MacConkey-type media in which glucose replaces lactose, enabling improved overall recovery of enterobacteria rather than specifically differentiating lactose fermenters.
Primary Applications
- Enumeration of Enterobacteriaceae in food, pharmaceuticals, and cosmetics
- Routine hygiene monitoring and quality control
- Post-enrichment plating for overall enterobacteria counts
- Useful where broader Enterobacteriaceae recovery is required
Key Features
- Glucose-based formulation for Enterobacteriaceae enumeration
- Bile salts and crystal violet inhibit Gram-positive bacteria
- Neutral red supports colony contrast and halo interpretation
- Classical medium for food and hygiene testing
Typical Composition / Product Characteristics
| Component / Attribute | Amount / Value | Function | Practical Role |
|---|---|---|---|
| Peptone from gelatin | 7.0 g/L | Primary nutrient source | Supports enterobacterial growth |
| Yeast extract | 3.0 g/L | Vitamin source | Enhances recovery |
| Sodium chloride | 5.0 g/L | Osmotic balance | Maintains suitable ionic strength |
| Bile salts | 1.5 g/L | Selective agent | Suppresses many Gram-positive organisms |
| Glucose | 10.0 g/L | Fermentable carbohydrate | Supports Enterobacteriaceae recovery |
| Neutral red | 0.03 g/L | Indicator | Helps visualize colony halos |
| Crystal violet | 0.002 g/L | Selective dye | Additional suppression of Gram-positive bacteria |
| Agar | 13.0 g/L | Solidifying agent | Forms plate medium |
| Final pH | 7.4 ± 0.2 | Optimized condition | Supports intended selectivity and readout |
Preparation, Incubation & Interpretation
Preparation
Suspend 39.5 g in 1 L distilled water. Bring to the boil to fully dissolve. Sterilize by boiling for about 1 minute with frequent agitation. Do not autoclave. Avoid prolonged heating.
Incubation / Use
Typical incubation is around 30–37°C for about 18–24 hours depending on the validated method.
Interpretation
Enterobacteriaceae typically produce dark red to purple colonies, often with reddish halos caused by glucose fermentation. Colony count and morphology should be interpreted according to the applicable standard method.
Comparative Media / Workflow Position
| Medium / Product | Primary Target | Principle | Typical Use | Key Advantage |
|---|---|---|---|---|
| VRBGA / VRBD | Enterobacteriaceae | Selective glucose agar | Food and hygiene enumeration | Broader enterobacteria recovery |
| VRBA | Coliforms | Selective lactose agar | Coliform enumeration | Focused on lactose-fermenting coliforms |
| MacConkey Agar | Gram-negative enterics | Bile/dye differential agar | General enteric differentiation | Widely used clinical medium |
| Endo / EMB | Coliforms and enterics | Differential indicator agar | Water and food work | Classic lactose-based differentiation |
Recommended Workflow
1. Prepare sample
Homogenize or dilute according to the validated food or hygiene method.
Homogenize or dilute according to the validated food or hygiene method.
2. Plate medium
Pour or surface-inoculate onto VRBG agar.
Pour or surface-inoculate onto VRBG agar.
3. Incubate
Use the standard incubation time and temperature for the target protocol.
Use the standard incubation time and temperature for the target protocol.
4. Count colonies
Enumerate typical Enterobacteriaceae colonies and confirm if required.
Enumerate typical Enterobacteriaceae colonies and confirm if required.
Strategic Use
Advantages
- Classical and widely used Enterobacteriaceae enumeration medium
- Good recovery of overall enterobacteria
- Useful in food, pharmaceutical, and cosmetic QC
Considerations
- Not designed to differentiate lactose-positive from lactose-negative enterics in the same way as VRBA
- Do not autoclave
- Interpretation should follow the method-specific colony criteria
Selection Guide
- Choose for Enterobacteriaceae counts rather than strict coliform counts
- Useful in routine food hygiene testing
- Good option when broader enterobacteria recovery is needed