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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Neutral red is employed as the pH indicator. Colonies of Enterobacter aerogenes often appear mucoid and pinkish in color.

Experimental Results: Experiment 4

Violet Red Bile Agar is a selective medium vvrb to detect and enumerate lactose-fermenting coliform microorganisms. Growth; pink to red colonies, may have a slight precipitate around colonies colonies.

Lactose-fermenting microorganisms produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile. The medium contains bile salts and crystal violet which serve as inhibitory agents toward some gram-positive microorganisms, especially staphylococci. Lactose-fermenting microorganisms, including coliforms, produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile.


Aseptically inoculate agar surface with 0. Hardy Diagnostics Violet Red Bile Agar is recommended for the detection of coliforms in food or dairy products.

Spread the dilution evenly over the surface of the medium. Alternatively, a covered, boiling waterbath degrees C.

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Violet Red Bile Agar contains a low concentration of bile salts, and therefore is not completely specific for enterics. Carefully swirl the plate to mix the inoculum evenly.

Melt agar by placing in a boiling waterbath until liquified. Heat in waterbath until melted.

Consult listed references for information concerning inoculation procedures. A covered waterbath will help to reach and maintain the temperature. Surface colonies of Escherichia coli appear as entire-edged colonies, while deep colonies appear lens-shaped. Allow medium to warm to room temperature prior to inoculation.

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

Consult listed references for information on sample collection. For melting bottled media: The medium is recommended for use in the microbiological analysis of milk and other dairy vr, and for use in the examination of water.


U Violet Red Bile Agar, 8oz. There should be enough water in the waterbath to reach the media line. Using a sterile spreader device, distribute the inoculum evenly over the agar surface.

Violet Red Bile Agar (VRBA) -Lab M

Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

Non-lactose-fermenting microorganisms result in colorless colonies. Non-lactose-fermenting microorganisms produce colorless colonies. Enterococci may grow, and if so, usually appear ahar in size and rose colored.

Prepare decimal dilutions in sterile diluent to obtain CFU per plate. This product is not intended to be used for the diagnosis of human disease. Standard microbiological supplies and equipment such as loops, slides, staining supplies, Lauryl Sulfate Broth, other culture media, microscopes, incinerators, and incubators, etc.

Place a 1ml inoculation into a sterile petri plate. vrh

Media should not be used if there are frb signs of deterioration shrinking, cracking, or discolorationcontamination, or if the expiration date has passed.

American Public Health Association.