R & F® Listeria monocytogenes Chromogenic Plating Medium (Licensed from Biosynth AG)
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Certificate of Analysis
SDS
SDS Listeria monocytogenes agar
SDS Listeria monocytogenes agar supplement
SDS Listeria monocytogenes plates
Highly Selective/Differential System For Identifying Listeria monocytogenes
Colony Appearance
Listeria monocytogenes (L.m.) and Listeria ivanovii (L.i.) appear as turquoise convex colonies, 1-2.5 mm in diameter, with or without a precipitate (halos) after 48 h at 35°C. All other Listeria sp. and a small percent of Enterococcus sp. will grow as white colored colonies. Bacillus sp. and Gram (-)s are inhibited. A quick and simple biochemical test on our confirmation medium biplate can easily distinguish, within 6 h, L. m. (fluorogenic reaction and/or acid production) from L.i.(negative for both).
Mechanism
Our plating medium contains the chromogen X- inositol phosphate (X-IP) that detects the enzyme phosphatidylinositol phospholipase C, virulence factor, which is found in L.m. and L.i. Bovine albumin is added for the enzyme to recognize the chromogenic substrate. Even though L.m. and L.i. are the same color, L.i. strains are very seldom found in foods. Our confirmatory medium biplate uses a quick fluorogenic reaction from α-mannosidase and an acid production from rhamnose to distinguish L.m. from L.i.
Industry Types
Fish, poultry, meat, dairy, bakery and ready-to-eat foods and environmental testing in food processing facilities.
See Product Brochure, Use Protocol, SDS, Certificate of Analysis and Medium Preparation for more information about our medium.
Advantages/Benefits
1. Our chromogenic medium was the only chromogenic L.m. collaboratively validated by the FDA.
2. Use a chromogenic reaction identifying a specific virulence factor, i.e. phoshpatidylinositol-specific phospholipase C.
3. Highly differential detection system identifies only the pathogenic Listeria species (L.m. & L.i.). Selectivity and sensitivity for L.m. & L.i. is 96% and 100%, respectively, with no false negatives (>100 L.m. & L.i. strains tested).
4. Water insoluble chromogenic lattice prevents the colony color from diffusing into the agar making detection and enumeration much easier.
5. Competitors’ non-chromogenic agars (MOX, Oxoid & Palcam) which depend on esculinase as the differential trait allows many Listeria sp., Bacillus sp. and Enterococcus sp. to grow as black color colonies. Since the end product is water soluble, the black color will diffuse into the medium. Additional expensive tests are required to further identify L.m. strains.
6. Competitors’ chromogenic media which utilize the X-β-D-glucopyranoside substrate will allow too many Listeria sp., Bacillus sp. and Enterococcus sp. to grow as blue colored colonies without clear halos. These colonies will interfere with the identification of L.m. & L.i. by coalescing together making it difficult to see the clear halo around the blue colony of the L.m. & L.i.
7. Our rapid and convenient fluorogenic/acid test differentiates L.m. from L.i. as quick as 6 hours-saving time and costs.
8. The shelf life of prepared plates remains stable for at least 60 days, stored in the dark at 2-8°C. One bottle of plating medium powder and two boxes of supplements will make approximately 230 plates.
9. Collaboratively validated by FDA and listed in their BAM.
Publications
*1. Restaino, L., E.W. Frampton, R.M. Irbe, G. Schabert and H. Spitz. 1999. Isolation and detection of Listeria monocytogenes using fluorogenic and chromogenic substrates for phoshatidylinositol-specific phospholipase. C. J. Food Prot. 62: 244-251.
*2. Hoffman, A. and M. Wiedmann. 2001. Comparative evaluation of culture and BAX polymerase chain reaction-based detection methods for Listeria spp. and Listeria monocytogenes in environmental and raw fish samples. J. Food Prot. 64: 1521-1526.
*3. Jinneman, K.C., J.M. Hunt, C.A. Eklund, J.S. Wernberg, P.N. Sado, J.M. Johnson, R.S. Richtor, S.T. Torres, E. Ayotte, S.J. Eliasberg, P. Istrafano, D. Bass, N. Kexel-Calabresa, W. Lin, and C.N. Barton. 2003. Evaluation and interlaboratory validation of a selective agar for phosphatidylinositol-specific phospholipase C activity using a chromogenic substance to detect Listeria monocytogenes from foods. J. Food Prot. 66: 441-445.
* BCM Listeria monocytogenes is R & F® Listeria monocytogenes
Ordering Information
M-0550
R & F® Listeria monocytogenes Chromogenic Detection System (250 g Bottle of Powder & two Supplement Boxes – Makes 220-240 Plates)
M-0500
R & F® Listeria monocytogenes Chromogenic Plating Medium (250 g Bottle)
M-0510
R & F® Listeria moncytogenes Supplement for Plating Medium (1 Box)
M-0520
R & F® Listeria moncytogenes Confirmatory Medium (100 g Bottle)
M-0560
R & F® Listeria monocytogenes Chromogenic Prepared Plate (Minimum Order of 20 Plates – Shelf life is 60 Days)
M-0570
R & F® Listeria monocytogenes Confirmatory Prepared Biplate (Minimum Order of 20 Plates – Shelf life is 60 Days)
