Dehydrated culture media
MRS Broth Low pH
Recommended medium for the growth of lactobacilli in general.
- Cat. No.
- LC-1431
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 8 °C
- Minimum guaranteed shelf life
- 15 months
MRS Broth Low pH is a selective medium that supports the good growth of lactobacilli in general.
Key features
Applications
Selective enrichment of lactobacilli.
Industry
Alcoholic beverages, dairy products, food.
Preparation
54 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
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 of the B-group. Dextrose is the fermentable carbohydrate.
The growth of some lactobacillus strains is inhibited at a pH higher than 6.0 and it is necessary to acidify the medium to favour the growth. With a pH of 5.7 ± 0.2, this medium favors the growth of these strains.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Amber, slightly opalescent |
| Final pH (25 °C) | 5.7 ± 0.1 |
| Amount per litre | 54 g |
| Storage | 2 to 8 °C |
Formula
| Ingredient | g/L |
|---|---|
| Dextrose | 20 |
| Enzymatic digest of casein | 10 |
| Dipotassium phosphate | 2 |
| Magnesium sulfate heptahydrate | 0.2 |
| Beef extract | 10 |
| Sodium acetate | 5 |
| Tween 80 | 1.08 |
| Yeast extract | 4 |
| Triammonium citrate | 2 |
| Manganese sulfate tetrahydrate | 0.05 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 54 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 15 minutes.
Instructions for use
Incubate at a temperature of 37 °C for 3 days or at 30 °C for 5 days.
Quality control
Microbiological test
Incubation conditions: 37 °C / 3 days; 30 °C / 5 days.
| Microorganism | Specification |
|---|---|
| Escherichia coliATCC 25922 | Partial/total inhibition |
| Pseudomonas aeruginosaATCC 27853 | Total inhibition |
| Lacticaseibacillus caseiATCC 393 | Good growth |
| Lactobacillus acidophilusATCC 4356 | Good growth |
| Lactobacillus fermentumATCC 9338 | Good/moderate growth |
Bibliography
- ROGOSA, M., a. SHARPE, M.E.: An approach to the classification of the lactobacilli. J. Appl. Bact., 22; 329-340 (1959).
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
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