Violet Red Bile Agar. M Violet Red Bile Agar is selective medium used for the isolation, detection and enumeration of coli-aerogenes bacteria in water, milk. Violet Red Bile Agar (VRB Agar). APHA / COMPF / IDF-FIL / ISO Medium for the detection and enumeration of coliforms in milk and other dairy products. Violet Red Bile Agar is used for the enumeration of coliforms in food and the presumptive test for coliforms uses Violet Red Bile Agar, (VRBA).

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Media should not be used if there are any signs of deterioration shrinking, cracking, or discolorationcontamination, or if the expiration date has passed. Alternatively, a covered, boiling waterbath degrees C.

Using a sterile spreader device, distribute the inoculum evenly over the agar surface. Allow medium to warm to room temperature prior to inoculation. Standard microbiological supplies and equipment such as loops, slides, staining supplies, Lauryl Sulfate Broth, other culture media, microscopes, incinerators, and incubators, etc.

Enterococci may grow, and if so, usually appear pinpoint in size and rose colored.


Non-lactose-fermenting microorganisms produce colorless colonies. This product is not intended to be used for the diagnosis of human disease. American Public Health Association.

For melting bottled media: Carefully swirl the plate to mix the inoculum evenly.

Experimental Results: Experiment 4

Aseptically inoculate agar surface aagar 0. A covered waterbath will help to reach and maintain the temperature. Lactose-fermenting microorganisms, including coliforms, produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile.

Surface colonies of Escherichia coli appear as entire-edged colonies, while deep colonies appear lens-shaped. Non-lactose-fermenting microorganisms result in colorless colonies. The medium is recommended for use in the microbiological analysis of milk and other dairy products, and agwr use in the examination of water.

Violet Red Bile Agar contains a low concentration of bile salts, and therefore is not completely specific for enterics. Consult listed references for information on sample collection.

Violet Red Bile (VRB) Agar – for the detection of coliforms

The medium contains bile salts and crystal violet which serve as inhibitory agents toward some gram-positive microorganisms, especially staphylococci. Consult listed references for information concerning inoculation procedures. Growth; pink to red colonies, may have a slight precipitate around colonies colonies. Prepare decimal dilutions in sterile diluent to obtain CFU per plate. Heat in waterbath until melted. Spread the dilution evenly over the surface of the medium.



U Violet Red Bile Agar, 8oz. Melt agar by placing in a boiling waterbath until liquified.

Product is light vrh temperature sensitive; protect from light, excessive heat, moisture, and freezing. Violet Red Bile Agar is a selective medium used to detect and enumerate lactose-fermenting coliform microorganisms. Lactose-fermenting microorganisms produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile.

Hardy Diagnostics Violet Red Bile Agar is recommended for the detection of coliforms in food or dairy products.

Colonies of Enterobacter aerogenes often appear mucoid and pinkish in color. Place a 1ml inoculation into a sterile petri plate.

There should be enough water in the waterbath to reach the media line. Neutral red is employed as the pH indicator.