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

Consult listed references for information on sample collection. A covered waterbath will help to reach and maintain the temperature.

Carefully swirl the plate to mix the inoculum evenly. Prepare decimal dilutions in sterile diluent to obtain CFU per plate. Consult listed references for information concerning inoculation procedures.

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


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

Place a 1ml inoculation into a sterile petri plate. Standard microbiological supplies and equipment such as loops, slides, staining supplies, Lauryl Sulfate Broth, other culture media, microscopes, incinerators, and incubators, etc.

Growth; pink to red colonies, may have a slight precipitate around colonies colonies.


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

Colonies of Enterobacter aerogenes xgar appear mucoid and pinkish in color. Using a sterile spreader device, distribute the inoculum evenly over the agar surface. Non-lactose-fermenting microorganisms produce colorless colonies. U Violet Red Bile Agar, 8oz.

Violet Red Bile Agar is a selective medium used to detect and enumerate lactose-fermenting coliform microorganisms. The medium 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 (VRBA) -Lab M

American Public Health Association. Alternatively, a covered, boiling waterbath degrees C.


Spread the dilution evenly over the surface of the medium. Violet Red Bile Agar contains a low concentration of bile salts, and therefore is not completely specific for enterics. For melting bottled media: Neutral red is employed as the pH indicator. Enterococci may grow, and if so, usually appear pinpoint in size and rose colored.

Surface colonies of Escherichia coli appear as entire-edged colonies, while deep colonies appear lens-shaped. There should be enough water in the waterbath to reach the media line. Non-lactose-fermenting microorganisms result in colorless colonies.

Experimental Results: Experiment 4

Melt agar by placing in a boiling waterbath until liquified. Allow medium to warm to room temperature prior to inoculation. This product is not intended to be used for the diagnosis of human disease. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.