Liofilchem Violet Red Bile Lactose Agar

Liofilchem's Violet Red Bile Lactose Agar is a selective medium designed for the isolation and enumeration of coliform bacteria in food, water, and other materials of sanitary importance. It is widely used in microbiological analysis following APHA and ISO 4832 guidelines.

Key Features:

1. Selective Properties:
   • Includes bile salts and crystal violet, which inhibit Gram-positive bacteria, allowing selective growth of coliforms.
   • Ideal for differentiating coliforms from other microbial contaminants.
2. Color-Indicated Results:
   • Utilizes Neutral Red as a pH indicator, which changes color depending on acid production from lactose fermentation.
3. Applications:
   • Recommended for food safety testing, water quality analysis, and other public health microbiology applications.
4. Compliance:
   • Conforms to ISO 4832 and APHA standards for enumeration of coliforms using pour plate or spread plate techniques.

Composition (Per Liter):

Final pH: 7.4 ± 0.2 at 25°C.

Preparation Instructions:

For Dehydrated Medium:

1. Suspend 40.5 g of powder in 1 liter of distilled or deionized water.
2. Heat to boiling, stirring frequently, until fully dissolved.
3. Do not autoclave.
4. Cool to 45-50°C and pour into sterile Petri dishes under aseptic conditions.

For Ready-to-Use Tubes/Bottles:

1. Melt the content in a water bath at 100°C (caps slightly loosened).
2. Ensure complete dissolution by turning the bottle/tube after screwing the cap tightly.
3. Cool to 45-50°C, mix well, and dispense.

Testing Procedure:

1. Dilution:
   • Perform serial dilutions of the test sample to achieve 10-150 colonies per plate.
2. Inoculation:
   • Use pour plate or spread plate method to inoculate the medium.
3. Incubation:
   • Incubate plates aerobically at 30°C or 37°C for 24 ± 2 hours, depending on the target organism.

For Environmental Monitoring:

• Use swabs or RODAC plates for surface sampling.
• For direct sampling, press the agar firmly against the test surface for a few seconds.

Result Interpretation:

• Coliforms:
  • Purplish-red colonies (≥ 0.5 mm diameter) indicate lactose fermentation.
• Atypical Colonies:
  • Smaller or differently colored colonies, especially those derived from milk products, should be confirmed using Brilliant Green Lactose Bile Broth 2% (ref. 20102).

Applications:

1. Food and Beverage Testing:
   • Assess coliform contamination in processed and raw food products.
2. Water Quality Analysis:
   • Evaluate sanitary quality of potable and recreational water.
3. Environmental Monitoring:
   • Test hygiene in industrial settings through surface and environmental sampling.

Appearance:

• Dehydrated Medium: Free-flowing, homogeneous, beige to reddish-beige.
• Prepared Medium: Slightly opalescent, reddish-purple.

Storage and Shelf Life:

• Dehydrated Medium:
  • Store at 10-30°C in a dry, sealed container.
  • Shelf life: 4 years.
• Prepared Plates:
  • Store at 10-25°C, away from light.
  • Shelf life: 6 months.

Quality Control:

Precautions:

1. For Professional Use Only:
   • Must be handled by trained microbiological professionals.
2. Non-Hazardous:
   • Contains no substances exceeding hazardous thresholds.
3. Avoid Contamination:
   • Ensure sterile techniques during preparation and handling.

Disposal:

• Dispose of waste as per national and local regulations.

Packaging:

References:

1. EN ISO 11133:2014. Microbiology of food, animal feed and water - Preparation, production, storage and performance testing of culture media.
2. ISO 4832:2006. Horizontal method for the enumeration of coliforms - Colony count technique.
3. Standard Methods for the Microbiological Examination of Dairy Products, 17th ed. APHA.
4. Compendium of Methods for the Microbiological Examination of Foods, 4th ed. APHA.

Liofilchem Violet Red Bile Lactose Agar offers a reliable and standardized method for detecting and quantifying coliforms in various samples. Its selective properties, ease of use, and compliance with international standards make it a valuable tool in microbiological quality assurance across multiple industries.