Chromogenic media
E. coli-Enterobacteria Chromogenic Agar
For the differentiation of E. coli and enterobacteria in foods.
- Cat. No.
- LC-2018
- Category
- Chromogenic media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 12 months
E. coli-Enterobacteria Chromogenic Agar is used for the differentiation of E. coli from the rest of enterobacteria. In the same plate it is able to enumerate E. coli and enterobacteria.
Key features
Applications
Differentiation of enterobacteria and Escherichia coli.
Industry
Food.
Preparation
30.5 g in one liter of distilled water; boil for one minute, avoid overheating, do not autoclave.
Principles and uses
The medium can be inoculated directly with a loop. E. coli is easily distinguishable due to the dark blue-greenish blue colony color. Enterobacteria will grow as magenta colonies. The rest of bacteria are inhibited and, in case of growing, they will grow as colorless colonies.
Note: Some Shigella strains contain the same enzyme as E. coli and can grow as light blue colonies. E. coli O157:H7 does not contain the enzyme to produce blue colonies and will grow magenta.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Amber, slightly opalescent |
| Final pH (25 °C) | 7.1 ± 0.2 |
| Amount per litre | 30.5 g |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 14 |
| Chromogenic mixture | 0.5 |
| Nutrients | 16 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 30.5 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. AVOID OVERHEATING. DO NOT AUTOCLAVE. Cool to 45-50 °C, mix well and dispense into plates.
Instructions for use
Inoculate and incubate at 35 ± 2 °C for 18-24 hours.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 18-24 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Shigella flexneriATCC 12022 | Good growth | Pink colonies |
| Salmonella enteritidisATCC 13076 | Good growth | Pink colonies |
| Salmonella typhimuriumATCC 14028 | Good growth | Pink colonies |
| Escherichia coliATCC 25922 | Good growth | Dark blue-greenish blue colonies |
| Enterococcus faecalisATCC 29212 | Total inhibition | |
| Staphylococcus aureusATCC 6538 | Total inhibition | |
| Escherichia coliATCC 8739 | Good growth | Dark blue-greenish blue colonies |
Bibliography
- Alonso, J.L. Soriano, K., Amoros I., Ferrus, M.A. 1998 Quantitative determination of E. coli and fecal coliforms in water using a chromogenic medium. J. Environ. Sci Health 33.
- Journal Clinical Microbiology, Vol. 41 No. 7 p. 3229-3232. July 2003. Robert Cassar and Paul Cuschieri.
- J.D. Perry, Michael Furs, Jeffrey Taylor, et al. Journal Clinical Microbiology, March 1999, pag. 766-768 Vol. 37. No. 3.
- Gallioto di camillo, p. et al. J. Clin. Microbiol. March 1999.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
Every lot comes with its certificate.
Tracked shipment
Follow your shipment live, from our warehouse to your lab.
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Frequently asked questions
Can I ask for formats other than those listed?
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