Dehydrated culture media
MRS Broth w/o Dextrose
Medium to facilitate the growth of lactobacilli.
- Cat. No.
- LC-1295
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
MRS Broth w/o Dextrose provides the user with the ability to incorporate a desired carbohydrate for additional selectivity.
Key features
Applications
Selective enrichment of lactobacilli.
Industry
Dairy products, food.
Preparation
35.15 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 12 minutes.
Principles and uses
It was developed by de Man, Rogosa and Sharpe to provide a medium that would support the good growth of lactobacilli, but in particular for those strains which showed poor growth in existing media such as L. brevis and L. fermenti, replacing a variable product (tomato juice). The medium is apt for the growth of lactic acid bacteria, including Lactobacillus, Pediococcus and Leuconostoc.
Ammonium citrate at a low pH inhibits most microorganisms, but allows the growth of lactobacilli. Dipotassium phosphate and sodium acetate are buffer agents to maintain a low pH. Tween 80 is an emulsifier; manganese and magnesium sulfates are sources of ions and sulfate. Bacteriological peptone and beef extract provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly the B-group.
The growth of some Lactobacillus strains is inhibited at a higher pH of 6.0 and it is necessary to acidify the medium to promote the growth. To acidify the medium some drops of acetic acid can be added.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Clear amber |
| Final pH (25 °C) | 6.5 ± 0.2 |
| Amount per litre | 35.15 g |
Formula
| Ingredient | g/L |
|---|---|
| Dipotassium phosphate | 2 |
| Magnesium sulfate | 0.1 |
| Manganese sulfate | 0.05 |
| Beef extract | 10 |
| Polysorbate 80 | 1 |
| Sodium acetate | 5 |
| Yeast extract | 5 |
| Peptone Proteose No. 3 | 10 |
| Ammonium citrate | 2 |
Preparation and use
Preparation
Suspend 35.15 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 appropriate containers and sterilize in autoclave at 121 °C for 12 minutes.
Instructions for use
Inoculate and incubate at 33-37 °C for 18-24 hours.
Quality control
Microbiological test
Incubation conditions: 33-37 °C / 18-24 h.
| Microorganism | Specification |
|---|---|
| Lactobacillus sakeiATCC 15521 | Good growth |
| Lactococcus lactis ssp. lactisATCC 19435 | Good growth |
| Lactobacillus fermentumATCC 9338 | Good growth |
Bibliography
- Sharpe M. Elisabeth, Fryer T.F. and Smith D.G. (1966) "Identification of the Lactic Acid Bacteria in Identification Method for Microbiologist Part A" (Gibbs B.M. and Skinner F.A. eds.) London and New York, Academic Press.
- Briggs M. (1953) J. Dairy Res., 20: 36-40.
- Reuter G. (1985) Intern. J. Food Microbiol 2: 55-68.
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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