(AB) Violet Red Bile Agar, 500 grams

Violet Red Bile Agar is recommended for use in the microbiological analysis of milk and other dairy products and for use in the examination of water. Violet Red Bile Agar is a selective medium which detects the growth of lactose fermenting coliforms. Coliforms colonies lower the pH of the medium subsequently causing their colonies to look red (neutral red dye) and to precipitate the bile salts. Crystal violet and bile salts inhibit the growth of Gram positive microorganisms. Agar medium is used for the detection and determination of coliforms in food, milk, water and other sanitary materials. (Alpha Biosciences # V22-100-500gm)

Use: Agar medium is used for the detection and determination of coliforms in food, milk, water and other sanitary materials.

Description: Violet Red Bile Agar is recommended for use in the microbiological analysis of milk and other dairy products and for use in the examination of water. Violet Red Bile Agar is a selective medium which detects the growth of lactose fermenting coliforms. Coliforms colonies lower the pH of the medium subsequently causing their colonies to look red (neutral red dye) and to precipitate the bile salts. Crystal violet and bile salts inhibit the growth of Gram positive microorganisms.

Formula* per Liter:

• Pancreatic Digest of Gelatin........... 7.0g
• Lactose ..........................................10.0g
• Yeast Extract .................................... 3.0g
• Sodium Chloride............................. 5.0g
• Bile Salts #3 .................................... 1.5g
• Neutral Red ................................... 0.03g
• Agar .................................................15.0g
• Crystal Violet .............................. 0.002g

Final pH: 7.4 ± 0.2 at 25.0°C

* Grams per liter may be adj. or formula supplemented to obtain desired performance

Preparation: Mix 41.5 grams of the medium in one Liter of purified water until evenly dispersed. Heat with repeated stirring and boil for two minutes. DO NOT AUTOCLAVE. Cool to 40° to 45°C and dispense 15-20 mL into 100 mm Petri dishes containing inoculum. After solidification of the inoculated medium, evenly add a cover of 4 mL of the cooled (45°- 46.0°C) agar medium.

Quality Control Specifications:

1. The powder is homogeneous, free flowing and light reddish-beige.
2. Visually the prepared medium is clear to slightly hazy and reddish purple.
3. Expected cultural response after 18-24 hours at 35.0°C.

Organism                                                                        Result

Enterobacter aerogenes ATCC 13048             Growth, Pink to red colonies

Escherichia coli ATCC 25922                           Growth, Pink to red colonies

Salmonella typhimurium ATCC 14028               Growth, Clear colonies

Staphylococcus aureus ATCC 25923                     Growth Inhibited

Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original light pinkish-beige color.