Dehydrated culture media
DEV Lactose Broth
For the detection of lactose-degrading microorganisms.
- Cat. No.
- LC-1421
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
DEV Lactose Broth is used especially for the identification of E. coli and coliform bacteria in bacteriological analysis of water according to German standard methods for the examination of water and drinking water.
Key features
Applications
Detection of lactose fermenters.
Industry
Food, water.
Preparation
28 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
It is not a selective medium, but it is used as a presumptive medium for the detection of coliforms in water and food, and is also used for the determination of lactose-fermenting bacteria. It is commonly used with Durham fermentation tubes for the examination of gas formation.
Meat peptone and beef extract provide nitrogen, vitamins, minerals and amino acids essential for growth. Lactose is the fermentable carbohydrate providing carbon and energy. The fermentation of lactose is shown by the acidification of the medium that causes the pH indicator (bromocresol purple) to turn yellow, as well as by gas production in Durham tubes.
E. coli and coliforms can ferment lactose with gas production and therefore the color of the medium changes to yellow.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Clear beige |
| Color of the prepared medium | Purple |
| Final pH (25 °C) | 7.2 ± 0.2 |
| Amount per litre | 28 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bromocresol purple | 0.02 |
| Lactose | 10 |
| Beef extract | 3 |
| Meat peptone | 10 |
| Sodium chloride | 5 |
Preparation and use
Preparation
Suspend 28 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 and dispense into tubes. Sterilize in autoclave at 121 °C for 15 minutes. AVOID OVERHEATING.
Instructions for use
According to the German regulations:
- Take the inoculum with a sterile loop.
- Submerge the loop into the medium and shake gently.
- Incubate at 35 °C for 44 ± 4 hours.
Quality control
Microbiological test
Incubation conditions: 35 °C / 44 ± 4 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Klebsiella pneumoniaeATCC 13883 | Good growth | The medium changes to a yellow color, gas (+) |
| Salmonella typhimuriumATCC 14028 | Good growth | The medium does not change to yellow color, gas (-) |
| Escherichia coliATCC 25922 | Good growth | The medium changes to a yellow color, gas (+) |
| Enterococcus faecalisATCC 29212 | Good growth | Medium changes slightly to yellow, gas (-) |
| Aeromonas hydrophilaATCC 7966 | Good growth | The medium does not change to yellow color, gas (-) |
Bibliography
- Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung. - VCH Verlagsgesellschaft, D-6940 Weinheim.
- Verordnung über Trinkwasser und über Wasser für Lebensmittelbetriebe vom 12. Dezember 1990. - Bundesgesetzbl., Teil I; 2613-2629 (1990).
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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