Ready-to-use media
MRS Agar Low pH ISO
Solid medium for the culture of lactic acid bacteria according to de Man, Rogosa and Sharpe, modified according to ISO standards and IFU methods.
- Cat. No.
- LC-813
- Category
- Ready-to-use media
- Formats
- 2 formats
- ISO 17025 quality control
- Yes
- Minimum order
- 15 packs
- Standards
- ISO 15214
- Also available
- Dehydrated medium, 1 format (LC-1433)
The MRS medium is an improved modification that replaces the media previously used for the cultivation of lactobacilli, all based on the nutritional properties of tomato juice. The addition of magnesium, manganese acetate, and polysorbate enhances the growth of lactobacilli, even the most fastidious species such as Lactobacillus brevis and Lactobacillus fermenti.
Key features
Applications
Selective enrichment of lactobacilli.
Industry
Alcoholic beverages, dairy products, food.
Standards
ISO 15214.
Testing
Microbiological control according to ISO 11133:2014/Amd 1:2018.
Description and technique
Description
The high quality of peptones and supplements, meat and yeast extracts, provides growth factors necessary to make MRS one of the most complete media for the cultivation of lactobacilli. But selectivity is scarce and it often tends to have contaminants, which require a greater selection. For this, alternate subcultures on double layer solid medium and broth are recommended. In many cases growth is favored by an atmosphere enriched in CO₂.
MRS medium is especially suited for enumeration and maintenance of lactobacilli in plate by mass inoculation and covering with a second layer of molten medium, which usually avoids the need for the CO₂ enriched atmosphere, especially in the first isolation.
Technique
Collect, dilute and prepare samples and volumes as required according to specifications, directives, official standard regulations and/or expected results.
Melt the medium contained in the bottles in a water bath or in a microwave oven, avoiding overheating, before pouring into Petri dishes when cooled to room temperature.
Once solidified on a flat surface, spread the plate by streaking methodology or by spiral method.
Incubate in a 5% CO₂ atmosphere at 30 ± 1 °C for 72 ± 3 h.
After incubation, enumerate all the colonies that have appeared onto the surface of the agar.
Each laboratory must evaluate the results according to their specifications.
Presentation
| Code | Presentation | Filling | Packaging |
|---|---|---|---|
| LC-4684 | 10 prepared bottles, 250 mL | 200 ± 5 mL | 1 box with 10 bottles 250 mL. Metal non-injectable cap. |
Composition
| Ingredient | g/L |
|---|---|
| Enzymatic digest of casein | 10.00 |
| Meat extract | 10.00 |
| Yeast extract | 4.00 |
| D(+)-Glucose | 20.00 |
| Sodium acetate | 5.00 |
| Triammonium citrate | 2.00 |
| Magnesium sulfate | 0.20 |
| Manganese sulfate | 0.05 |
| Dipotassium phosphate | 2.00 |
| Polysorbate 80 | 1.08 |
| Agar | 14.00 |
Quality control
Physical/chemical control
| Color | Yellowish-brown |
|---|---|
| pH | 5.7 ± 0.2 at 25 °C |
Microbiological control
Melting - pour plates - inoculation: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ CFU (selectivity).
Microbiological control according to ISO 11133:2014/Amd 1:2018.
Microaerophilic incubation at 30 ± 1 °C for 72 ± 3 h.
| Microorganism | Growth |
|---|---|
| Escherichia coliATCC 25922, WDCM 00013 | Inhibited |
| Lactobacillus sakeiATCC 15521, WDCM 00015 | Good (≥ 70%) |
| Lactococcus lactisATCC 19435, WDCM 00016 | Good (≥ 70%) |
| Pediococcus pentosaceusATCC 33316, WDCM 00158 | Good (≥ 70%) |
| Bacillus cereusATCC 11778, WDCM 00001 | Inhibited |
Sterility control
Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.
Check at 7 days after incubation in same conditions.
Bibliography
- DOWNES, F.P. & K. ITO (2001) Compendium of Methods for the Microbiological Examination of Foods. 4th Ed. APHA. Washington DC. USA.
- FIL-IDF Standard 146 (2003) Yoghurt. Identification of characteristic micro-organisms.
- FIL-IDF Standard 192 (2006) Enumeration of presumptive Lactobacillus acidophilus on a selective medium. - Colony-count technique at 37 °C.
- IFU Method No 5 (1996) Lactic Acid Bacteria Count Procedure. Schweizerischer Obstverband. CH-6302 Zug.
- IFU Method No 9 (1998) Microbiological examination of potential spoilage micro-organisms of tomato products. Schweizerischer Obstverband. CH-6302 Zug.
- ISO Standard 11133 (2014) Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
- ISO Standard 15214 (1998) Horizontal method for the enumeration of mesophilic lactic acid bacteria - Colony count technique at 30 °C.
- ISO Standard 20128 (2006) Milk products. Enumeration of presumptive Lactobacillus acidophilus on a selective medium. - Colony-count technique at 37 °C.
- ISO Standard 9232 (2003) Yoghurt - Identification of characteristic microorganisms (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus).
- MAN, J.C. de, ROGOSA, M. y SHARPE, M. Elisabeth (1960) A medium for the cultivation of lactobacilli. J. Appl. Bact.; 23:130.
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?
Yes: custom formats and OEM packs are available on request. Tell us the quantities you need.
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