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    Violet Red Bile Agar: Composition

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    Muhammad Adnan
    Violet Red Bile Agar is a selective medium used to isolate and detect coli-aerogenes bacteria from samples like water, milk and clinical samples. It contains nutrients, dyes and bile salts that allow target bacteria to grow while inhibiting other organisms. Colonies are identified by their color and morphology.

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    Violet Red Bile Agar: Composition

    Uploaded by

    Muhammad Adnan
    39 views2 pages
    Violet Red Bile Agar is a selective medium used to isolate and detect coli-aerogenes bacteria from samples like water, milk and clinical samples. It contains nutrients, dyes and bile salts that allow target bacteria to grow while inhibiting other organisms. Colonies are identified by their color and morphology.

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    Media

    Original Title

    M049_2

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    Violet Red Bile Agar is a selective medium used to isolate and detect coli-aerogenes bacteria from samples like water, milk and clinical samples. It contains nutrients, dyes and bile salts that allow target bacteria to grow while inhibiting other organisms. Colonies are identified by their color and morphology.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    39 views2 pages

    Violet Red Bile Agar: Composition

    Uploaded by

    Muhammad Adnan
    Violet Red Bile Agar is a selective medium used to isolate and detect coli-aerogenes bacteria from samples like water, milk and clinical samples. It contains nutrients, dyes and bile salts that allow target bacteria to grow while inhibiting other organisms. Colonies are identified by their color and morphology.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
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    Violet Red Bile Agar


    M049
    Violet Red Bile Agar is selective medium used for the isolation, detection and enumeration of coli-aerogenes bacteria in
    water, milk, other dairy food products and also from clinical samples.
    Composition**
    Ingredients Gms / Litre
    Peptic digest of animal tissue 7.000
    Yeast extract 3.000
    Sodium chloride 5.000
    Bile salts mixture 1.500
    Lactose 10.000
    Neutral red 0.030
    Crystal violet 0.002
    Agar 15.000
    Final pH ( at 25C) 7.40.2
    **Formula adjusted, standardized to suit performance parameters
    Directions
    Suspend 41.53 grams in 1000 ml distilled water. Heat with stirring to boiling to dissolve the medium completely. DO NOT
    AUTOCLAVE. Cool to 45C and pour into sterile Petri plates containing the inoculum.
    If desired, the medium can be sterilized by autoclaving at 15 lbs pressure at 15lbs pressure (121C) for 15 minutes.
    Principle And Interpretation
    The coliform group consists of several genera of bacteria belonging to the family Enterobacteriaceae . The historical
    definition of this group has been based on the method used for detection i.e. lactose fermentation. This group is defined as
    all aerobic and facultative anaerobic, gram-negative, non-spore-forming rod shaped bacteria that ferment lactose with gas and
    acid formation within 48 hour at 35C (1, 2). Examination of foods, ingredients and raw materials, for the presence of marker
    groups such as coliforms is the one of the common tests.
    Violet Red Bile Agar, a modification of MacConkeys original formulation (3) is used for the enumeration of coli-aerogenes
    bacterial group. It relies on the use of the selective inhibitory components crystals violet and bile salts and the indicator system
    lactose, and neutral red. Thus, the growth of many unwanted organisms is suppressed, while tentative identification of sought
    bacteria can be made. Organisms, which rapidly attack lactose, produce purple colonies surrounded by purple halos. Non-
    fermenters or late lactose-fermenters produce pale colonies with greenish zones (4). VRBA is recommended by APHA (2,5).
    Selectivity of VRBA can be increased by incubation under anaerobic conditions and/ or at elevated temperature, i.e. equal to
    or above 42C (6-8).
    Peptic digest of animal tissue and yeast extract serve as sources of carbon, nitrogen, vitamins and other essential growth
    nutrients. Lactose is the fermentable carbohydrate, utilization of which leads to the production of acids. Neutral red indicator
    detects the acidity so formed. Crystal violet and bile salts mixture help to inhibit the accompanying gram-positive and unrelated
    flora. Sodium chloride maintains the osmotic equilibrium. Violet Red Bile Agar is not completely specific for enteric; other
    accompanying bacteria may give the same reaction. Further biochemical tests are necessary for positive identification (7).
    Quality Control
    Appearance
    Light yellow to pink homogeneous free flowing powder
    Gelling
    Firm, comparable with 1.5% Agar gel.
    Colour and Clarity of prepared medium
    Reddish purple coloured clear to slightly opalescent gel forms in Petri plates.
    HiMedia Laboratories Technical Data
    HiMedia Laboratories Pvt. Ltd. A-516,Swastik Disha Business Park,Via Vadhani Ind. Est., LBS Marg, Mumbai-400086, India. Customer care No.: 022-6147
    1919 Email: techhelp@himedialabs.com
    Reaction
    Reaction of 4.15% w/v aqueous solution at 25C. pH : 7.40.2
    pH
    7.20-7.60
    Cultural Response
    M049: Cultural characteristics observed after an incubation at 35-37C for 18-24 hours.
    Organism Inoculum
    (CFU)
    Growth Recovery Colour of
    colony
    Cultural Response
    Enterobacter aerogenes
    ATCC 13048
    50-100 luxuriant >=50% pink to pinkish
    red
    Escherichia coli ATCC
    25922
    50-100 luxuriant >=50% pinkish red
    with bile
    precipitate
    Salmonella Enteritidis ATCC
    13076
    50-100 luxuriant >=50% Colourless to
    orangish yellow
    Staphylococcus aureus
    ATCC 25923
    >=10 inhibited 0%
    Storage and Shelf Life
    Store below 30C in tightly closed container and the prepared medium at 2 - 8C. Use before expiry date on the label.
    Reference
    1. Eaton A. D., Clesceri L. S. and Greenberg A. E., (Ed.), 1998, Standard Methods for the Examination of Water and
    Wastewater, 20th Ed., American Public Health Association, Washington, D.C.
    2. Downes F. P. and Ito K., (Ed.), 2001, Compendium of Methods for the Microbiological Examination of Foods, 4th Ed.,
    American Public Health Association, Washington, D.C.
    3. MacConkey A., 1905, J. Hyg., 5, 333-379
    4. Corry J. E. L., Curtis G. D. W. and Baird R. M., (Ed.), 1995, Culture Media for Food Microbiology, Vol. 34, Progress in
    Industrial Microbiology, Elsevier, Amsterdam.
    5. Marshall R. T., (Ed.), 1992, Standard Methods for the Examination of Dairy Products, 16th Ed., APHA, Washington, D. C.
    5. International Organization for Standardization (ISO), 1991, Draft ISO/DIS 4382
    6. Mossel D. A. A. and Vega C. L., 1973, Hlth. Lab. Sci., 11:303
    7. Mossel D. A. A., Eclderink I., Koopmans M. and Van Rossem F., 1979, Food Protect., 42 : 470
    8. Mossel D. A. A. et al, 1986, J. Appl. Bacteriol., 60:289.
    Revision : 1 / 2011
    Disclaimer :
    User must ensure suitability of the product(s) in their application prior to use. Products conform solely to the information contained in
    this and other related HiMedia publications. The information contained in this publication is based on our research and development
    work and is to the best of our knowledge true and accurate. HiMedia Laboratories Pvt Ltd reserves the right to make changes to
    specifications and information related to the products at any time. Products are not intended for human or animal or therapeutic use but
    for laboratory,diagnostic, research or further manufacturing use only, unless otherwise specified. Statements contained herein should not
    be considered as a warranty of any kind, expressed or implied, and no liability is accepted for infringement of any patents.

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