Dehydrated culture media
Slanetz-Bartley Medium ISO
For the detection and enumeration of enterococci in water by the membrane filtration technique.
- Cat. No.
- LC-1109
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
- Standards
- ISO 11133ISO 7899-2
- Also available
- Ready-to-use medium, 2 formats (LC-946)
Slanetz-Bartley Medium is very selective for enterococci. Burkwall and Hartman demonstrated that the addition of 0.5 mL of Tween 80 and 20 mL of a 10% sodium carbonate or bicarbonate solution to each liter of the medium was valuable when investigating enterococci in frozen foods.
Key features
Applications
Detection and selective enumeration of enterococci.
Industry
Water.
Standards
ISO 11133, ISO 7899-2.
Preparation
41.5 g in one liter of distilled water; boil for one minute, avoid overheating, do not autoclave.
Principles and uses
Tryptose provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Glucose is the fermentable carbohydrate providing carbon and energy. Dipotassium phosphate is a buffer. Sodium azide inhibits Gram-negative bacteria. Triphenyltetrazolium chloride is reduced to formazan by the enterococci. Bacteriological agar is the solidifying agent.
It is prepared according to ISO 7899-2.
This medium also complies with the recommendations of the British Ministry of Health - Report 71, and the German DIN Regulations 10181 and 10160 for the examination of milk, meat and meat products.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Amber, slightly opalescent with a pink tint |
| Final pH (25 °C) | 7.2 ± 0.1 |
| Amount per litre | 41.5 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Glucose | 2 |
| Bacteriological agar | 10 |
| Sodium azide | 0.4 |
| Tryptose | 20 |
| Yeast extract | 5 |
| Triphenyltetrazolium Chloride (TTC) | 0.1 |
| Dipotassium hydrogen phosphate | 4 |
Preparation and use
Preparation
Suspend 41.5 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 50-60 °C, mix well and dispense into plates.
According to ISO 7899-2
For the detection and enumeration of enterococci according to ISO 7899-2:
- Filter a measured volume of water through a membrane filter.
- Place the membrane on a Slanetz-Bartley Medium plate.
- Incubate at 36 ± 2 °C for 44 ± 4 h.
- Transfer the membrane with characteristic colonies previously incubated in the Slanetz-Bartley medium, without inverting the membrane, to a plate with Bile Esculin Azide Agar (LC-1005), pre-heated to 44 °C.
- Incubate at 44 ± 0.5 °C for 2 hours.
- Read the plate immediately.
- It is considered that the typical colonies that show a brown-black color in the surrounding medium give positive reactions and are counted as intestinal enterococci.
Quality control
According to ISO 11133
Incubation conditions: 36 ± 2 °C / 44 ± 4 h.
Inoculation conditions: productivity quantitative (100 ± 20 CFU, min. 50 CFU) / selectivity (10⁴-10⁶ CFU).
Reference media: TSA.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Enterococcus faecalisATCC 19433 | Good growth > 50% | Red-brown-pink colonies |
| Escherichia coliATCC 25922 | Total inhibition (0) | |
| Staphylococcus aureusATCC 25923 | Total inhibition (0) | |
| Enterococcus faecalisATCC 29212 | Good growth > 50% | Red-brown-pink colonies |
| Enterococcus faeciumATCC 6057 | Good growth > 50% | Red-maroon-pink colonies |
Bibliography
- Slanetz L.W. and Bartley C.H. 1957. J. Bact. 74; 591-595.
- ISO 7899-2. Water quality - Detection and enumeration of intestinal enterococci - Part 2: Membrane filtration method.
- Nordic Committee of Food analysis 1968 Leaflet 68.
- Department of Health and Social Security report 711982.
- The Bacteriological examination of drinking water supplies, HMSO, London.
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