Dehydrated culture media
Lauryl Sulfate Agar
Selective isolation and enumeration of coliforms.
- Cat. No.
- LC-1309
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
Lauryl Sulfate Agar is a selective medium used in the presumptive detection of coliforms in waters, dairy products, seafood and foods, according to APHA Standard Methods, and by using the membrane filtration technique.
Key features
Applications
Selective enumeration and selective isolation of coliforms.
Industry
Dairy products, food, water.
Preparation
92.2 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
The coliform group is both aerobic and facultative anaerobic, Gram-negative, non-spore forming rods which ferment lactose producing acid and gas at 35 °C within 48 hours.
Casein peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is the source of vitamins, particularly of the B-group. Lactose is a fermentable complex carbohydrate energy source. Sodium lauryl sulfate is the selective agent used to inhibit organisms other than coliforms. Sporulating aerobic bacteria are completely inhibited. Phenol red is a pH indicator. Bacteriological agar is the solidifying agent.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige pink |
| Color of the prepared medium | Red |
| Final pH (25 °C) | 7.4 ± 0.2 |
| Amount per litre | 92.2 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 15 |
| Casein peptone | 40 |
| Lactose | 30 |
| Phenol red | 0.2 |
| Sodium lauryl sulfate | 1 |
| Yeast extract | 6 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 92.2 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. Sterilize in autoclave at 121 °C for 15 minutes. Cool to 45-50 °C, mix well and dispense into plates.
Instructions for use
Membrane filtration method:
- Filter an appropriate volume of the sample through the membrane.
- Place the membrane on the surface of the agar plate, avoiding the formation of air bubbles.
- Invert the plates and incubate at 35 ± 2 °C for 24-48 hours.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 24-48 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Klebsiella aerogenesATCC 13048 | Good growth | Colony color: yellow |
| Enterococcus faecalisATCC 19433 | Inhibited growth | |
| Escherichia coliATCC 25922 | Good growth | Colony color: yellow |
Bibliography
- APHA 1998. Standard Methods for the examination of water and wastewater, 20th edition.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
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Tracked shipment
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