Dehydrated culture media
Glucose OF Medium ISO
For the identification of Enterobacteriaceae.
- Cat. No.
- LC-2150
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
- Standards
- ISO 21528
- Also available
- Ready-to-use medium, 1 format (LC-4026)
Glucose OF Medium is used to confirm Enterobacteriaceae colonies in products intended for human consumption and the feeding of animals, and environmental samples in the area of primary production, food production and food handling.
Key features
Applications
Confirmation of enterobacteria.
Industry
Food.
Standards
ISO 21528.
Preparation
21.38 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
Enzymatic digest of casein provides nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Dipotassium phosphate acts as a buffer system. Glucose is the fermentable carbohydrate providing carbon and energy. Bromothymol blue is the pH indicator. Bacteriological agar is the solidifying agent.
Colonies of presumptive Enterobacteriaceae should be confirmed by means of tests for the fermentation of glucose and the presence of oxidase. If the colonies are oxidase-negative and glucose-positive, the sample shall be regarded as being positive for Enterobacteriaceae.
ISO 21528 recommends this medium to confirm the presumptive colonies of Enterobacteriaceae by fermentation test.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige with green tint |
| Color of the prepared medium | Green |
| Final pH (25 °C) | 6.8 ± 0.2 |
| Amount per litre | 21.38 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Enzymatic digest of casein | 2 |
| Bromthymol blue | 0.08 |
| Glucose | 10 |
| Bacteriological agar | 4 |
| Sodium chloride | 5 |
| Dipotassium hydrogen phosphate | 0.3 |
Preparation and use
Preparation
Suspend 21.38 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. Dispense 10 mL of the medium into tubes and sterilize in autoclave at 121 °C for 15 minutes. Leave the tubes in vertical position.
Just before use, heat the medium in boiling water or flowing steam for 15 min to remove oxygen, then cool rapidly to the incubation temperature.
According to ISO 21528
For the confirmation of Enterobacteriaceae according to ISO 21528:
- Inoculate and overlay the surface of the medium with a minimum of 1 cm of sterile mineral oil to induce an anaerobic environment that forces the strain to carry out fermentation.
- Incubate the tubes at 37 °C for 24 ± 2 h.
- If a yellow colour is developed throughout the contents of the tube, the reaction is positive.
Quality control
Microbiological test
Incubation conditions: 37 °C / 24 ± 2 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Pseudomonas aeruginosaATCC 27853 | Good growth | With mineral oil overlay: green colour (-) / No mineral oil overlay: yellow colour only at the top of the tube (-) |
| Escherichia coliATCC 8739 | Good growth | With mineral oil overlay: yellow colour (+) / No mineral oil overlay: yellow colour (+) |
Bibliography
- ISO 21528:2017 Microbiology of the food chain - Horizontal method for the detection and enumeration of Enterobacteriaceae.
- Drigalsky, C. (1902) Uber ein Verfahren zum Nachweis der typhusbacillen.
What you receive
The product
Shipped under controlled temperature when the product requires it.
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