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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There should be enough water in the waterbath to reach the media line.

Prepare decimal dilutions in sterile diluent to obtain CFU per plate. Hardy Diagnostics Violet Red Bile Agar is recommended for the detection of coliforms in food or dairy products. Non-lactose-fermenting microorganisms result in colorless colonies. Violet Red Bile Agar contains a low concentration of bile salts, and therefore is not completely specific for enterics.


U Violet Red Bile Agar, 8oz. Spread the dilution evenly over the surface of the medium. Non-lactose-fermenting microorganisms produce colorless colonies.


Alternatively, a covered, boiling waterbath degrees C. The medium is recommended for use in the microbiological analysis of milk and other dairy products, and for use in the examination of water. Aseptically inoculate agar surface with 0. This product is not intended to be used for the diagnosis of human disease.

Carefully swirl the plate to mix the inoculum evenly. American Public Health Association. Violet Red Bile Agar is a selective medium used to detect and enumerate lactose-fermenting coliform microorganisms. Heat in waterbath until melted. Allow medium to warm to room temperature prior to inoculation.

Violet Red Bile Agar (VRB Agar) – Products – Scharlab,S.L. The Lab Sourcing Group

Vfb listed references for information concerning inoculation procedures. Lactose-fermenting microorganisms produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile.

Melt agar by placing in a boiling waterbath until liquified. For melting bottled media: The medium contains bile salts and crystal violet which serve as inhibitory agents toward some gram-positive microorganisms, especially staphylococci. Neutral red is employed as the pH indicator. Growth; agr to red colonies, may have a slight precipitate around colonies colonies.

Using a sterile spreader device, distribute the inoculum evenly over the agar surface. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing. A covered waterbath will help to reach and maintain the temperature.


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

Surface colonies of Escherichia coli appear as entire-edged colonies, while deep colonies appear lens-shaped. Media should not be used if there are any signs of deterioration shrinking, cracking, or discolorationcontamination, or if the expiration date has passed.

Consult listed references for information on sample collection. Colonies of Enterobacter aerogenes often appear mucoid and pinkish in color. Enterococci may grow, and if so, usually appear pinpoint in size and rose colored.

Lactose-fermenting microorganisms, including coliforms, produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile. 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.