Description
VRBA Agar Granule: Your Essential Tool for Coliform Detection
VRBA Agar is a specialized medium designed for the detection and enumeration of coliforms in milk, food, and other materials. This differential and mildly selective agar plays a crucial role in microbiological analysis, making it an indispensable choice for laboratories focused on food safety and quality assurance.
Key Ingredients and Their Functions
The formulation of VRBA Agar includes essential ingredients that support the growth of coliform bacteria:
- Peptic Digest of Animal Tissue (7.0 g/liter): Provides vital carbon and nitrogen sources.
- Yeast Extract (3.0 g/liter): Supplies additional growth nutrients, enhancing bacterial proliferation.
- Sodium Chloride (5.0 g/liter): Maintains osmotic balance, ensuring cellular integrity.
- Lactose (10.0 g/liter): Acts as a fermentable carbohydrate, essential for energy production.
- Bile Salts No.3 (1.5 g/liter): Inhibits Gram-positive bacteria, allowing selective growth of coliforms.
- Crystal Violet (0.002 g/liter): Further suppresses unwanted bacterial species.
- Neutral Red (0.03 g/liter): Serves as a pH indicator, facilitating easy identification of lactose fermenters.
- Agar (15.0 g/liter): Provides the necessary solidifying agent for the medium.
With a final pH of 7.4±0.2 at 25℃, this agar ensures optimal conditions for microbial growth.
Preparation Instructions
To prepare VRBA Agar, suspend 41.5 grams of the medium in one liter of deionized or distilled water. Mix thoroughly and heat with frequent agitation until boiling. After boiling for one minute, allow the medium to cool to 45-50℃ before pouring it into petri dishes. Important: Do not autoclave this medium, as it can alter its effectiveness.
Performance and Quality Control
For effective results, inoculate the prepared medium and incubate at 36±1℃ for 18-24 hours. The colonies of lactose-fermenting bacteria will appear red, with sizes indicating the number of colonies present. Occasionally, small punctiform red colonies may develop, representing intestinal cocci.
Appearance and Storage
The dehydrated VRBA Agar appears as a light red granule, while the prepared medium forms a purplish-red transparent gel. To ensure longevity, store the dehydrated agar tightly sealed at 5-30°C. It boasts a shelf life of three years from the date of manufacture. Prepared VRBA Agar can be stored at 2-8°C away from direct light.
Why Choose VRBA Agar?
Selecting VRBA Agar for coliform detection is essential for any laboratory engaged in food safety testing. Its formulation not only promotes the growth of beneficial coliforms but also inhibits the presence of undesirable microorganisms, allowing for accurate analysis. Additionally, VRBA Agar aligns with current food safety regulations, making it a reliable choice in today’s competitive market.
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