Dehydrated culture media
Peptone Water with Lactose
For the coliforms presence confirmation.
- Cat. No.
- LC-1357
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
Peptone Water with Lactose is used for the confirmation of coliform presence in water.
Key features
Applications
Confirmation of coliforms.
Industry
Water.
Preparation
25 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
Peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Lactose is the fermentable carbohydrate providing carbon and energy. Phenol red is a pH indicator and sodium chloride supplies essential electrolytes for transport and osmotic balance.
Coliforms ferment lactose with gas and acid production. Acid formation changes the pH of the medium with a resulting color change from red to yellow. When lactose is not fermented the color of the medium remains red.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Red |
| Final pH (25 °C) | 7.5 ± 0.2 |
| Amount per litre | 25 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Lactose | 10 |
| Peptone | 10 |
| Phenol red | 0.01 |
| Sodium chloride | 5 |
Preparation and use
Preparation
Suspend 25 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 into tubes with Durham gas collecting tubes for gas detection. Sterilize in autoclave at 121 °C for 15 minutes.
Instructions for use
Incubate at a temperature of 37 ± 1 °C and observe after 24-48 hours.
Gas production is demonstrated by the displacement of the medium from the Durham tube. Production of both acid and gas is a presumptive indication of the presence of coliforms.
Quality control
Microbiological test
Incubation conditions: 37 ± 1 °C / 24-48 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Escherichia coliATCC 25922 | Good growth | Medium color: yellow. Gas (+) |
| Proteus mirabilisATCC 29906 | Good growth | Medium color: red. (-) |
Bibliography
- ISO 9308-1 standards. Detection and enumeration of Escherichia coli and coliform bacteria - Part 1: Membrane filtration method.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
Every lot comes with its certificate.
Tracked shipment
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Frequently asked questions
Can I ask for formats other than those listed?
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