Ready-to-use media
R2A Agar. Irradiated EP/USP
Solid medium for the enumeration of heterotrophic microorganisms in treated waters according to Pharmacopoeial Method.
- Cat. No.
- LC-792
- Category
- Ready-to-use media
- Format
- 20 plates, 90 mm
- Storage
- 15 to 25 °C
- Minimum guaranteed shelf life
- 2 months
- Standards
- European Pharmacopoeia
R2A Agar was proposed in 1979 by Reasoner and Geldreich and a few years later accepted by the APHA as an alternative medium for the enumeration of stressed cells in treated potable water. The culture medium has also been adopted by the European Pharmacopoeia for the control of purified water.
Key features
Applications
Non-selective enumeration of mesophilic aerobes.
Industry
Clinical, final product quality control, pharmaceutical/veterinary.
Standards
European Pharmacopoeia.
Presentation
20 prepared plates, 90 mm, with 21 ± 2 mL.
Description and technique
Description
The use of nutrient-rich media like PCA or TSA allows the growth of most microbes, but does not permit the recuperation of stressed or chlorine-resistant organisms. Using a medium like R2A with low nutrients in combination with a lower temperature and longer incubation time, it is possible to induce the resuscitation of these damaged cells.
In R2A Agar the source of nitrogen is the peptone and yeast extract supplies the vitamins and growth factors. The source of carbon is dextrose, and magnesium sulfate and potassium phosphate maintain the osmotic pressure. The starch is a detoxifier and sodium pyruvate increases the recuperation of stressed cells. The agar acts as a gelling agent.
Technique
The water sample must be processed as quickly as possible. If it is not possible to process within the first 6 hours, the sample must be refrigerated, but not for more than 30 hours.
R2A Agar can be used for pour plates, streak plates or filtration. The pour plate method can affect the recovery capacity of the medium due to thermal shock when mixing molten agar with the sample. When incubating at 35 °C, an incubation period of 3-5 days is recommended. In most circumstances an incubation temperature of 20-25 °C for 5-7 days is more effective. Plates must be protected against dehydration.
Presentation
| Presentation | 20 prepared plates, 90 mm |
|---|---|
| Filling | 21 ± 2 mL |
| Packaging | 1 box with 2 packs of 10 plates/pack. Single BOPP film. Every pack exhibits an irradiation indicator stuck on the side of the bag (8-14 kGy), with desiccant. Lateral labelling. |
Composition
| Ingredient | g/L |
|---|---|
| Proteose peptone | 0.500 |
| Casein peptone | 0.500 |
| Yeast extract | 0.500 |
| Glucose | 0.500 |
| Soluble starch | 0.500 |
| Sodium pyruvate | 0.300 |
| Dipotassium phosphate | 0.300 |
| Magnesium sulfate | 0.024 |
| Agar | 15.000 |
Quality control
Physical/chemical control
| Color | Pale yellow |
|---|---|
| pH | 7.2 ± 0.2 at 25 °C |
Microbiological control
Membrane filtration; practical range 10-100 CFU (productivity) according to Eur. Pharm.
Aerobiosis. Incubation at 32.5 ± 2.5 °C. Reading at 24-72 h for bacteria and 5-7 days for yeasts and moulds.
Analytical methodology according to ISO 11133:2014/Amd 1:2018; A2:2020.
Ps. aeruginosa and E. coli: double incubation temperature 30-35 °C / 20-25 °C.
Microbiological control according to ISO 11133:2014/Amd 1:2018; A2:2020.
| Microorganism | Growth |
|---|---|
| Escherichia coliATCC 8739, WDCM 00012 | Good (≥ 70%) |
| Staphylococcus aureusATCC 6538, WDCM 00032 | Good (≥ 70%) |
| Bacillus subtilisATCC 6633, WDCM 00003 | Good (≥ 70%) |
| Aspergillus brasiliensisATCC 16404, WDCM 00053 | Good (≥ 70%) |
| Candida albicansATCC 10231, WDCM 00054 | Good (≥ 70%) |
| Ps. aeruginosaATCC 9027, WDCM 00026 | Good (≥ 70%) |
| E. coliATCC 8739, WDCM 00012 (20-25 °C) | Good (≥ 70%) |
| Ps. aeruginosaATCC 9027, WDCM 00026 (20-25 °C) | Good (≥ 70%) |
| Ps. aeruginosa (paraeruginosa)ATCC 9027, WDCM 00026 | Good (≥ 70%) |
| Ps. aeruginosa (paraeruginosa)ATCC 9027, WDCM 00026 (20-25 °C) | Good (≥ 70%) |
Sterility control
Incubation 48 h at 30-35 °C and 48 h at 20-25 °C: NO GROWTH.
Check at 7 days after incubation in same conditions.
Bibliography
- ATLAS, R.M. (1995) Handbook of Media for Environmental Microbiology. CRC Press. Boca Raton. Fla. USA.
- CLESCERI, L.S., A.E. GREENBERG and A.D. EATON (1998) Standard Methods for the Examination of Water and Wastewater. 20th ed. APHA Washington D.C. USA.
- EATON, A.D., A.E. GREENBERG and L.S. CLESCERI (1995). Standard Methods for the Examination of Water and Wastewater. 19th ed. APHA Washington D.C. USA.
- EUROPEAN PHARMACOPOEIA. 10th ed. Suppl 6.3 (2020). General Monographs. Water for injections. (pg. 4339) EDQM. Council of Europe. Strasbourg.
- GREENBERG, A.E., R.R. TRUSSELL and L.S. CLESCERI (1985). Standard Methods for the Examination of Water and Wastewater. 16th ed. APHA-AWWA-WPCF. Washington D.C. USA.
- REASONER, D.J. and E.E. GELDREICH (1979) A new Medium for the enumeration and subculture of bacteria from potable water. Abstracts of Annual Meeting. ASM 79th Meeting. Paper #N7.
- Van SOETSBERGER, A.A. and C.H. LEE (1969) Pour plates or streak plates? Appl. Microbiol. 18:1092-1094.
What you receive
The product
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