R3A Agar – 250g | Low-Nutrient Medium for Drinking Water Heterotrophic Plate Count (HPC)
R3A Agar is a low-nutrient culture medium optimized for detecting heterotrophic bacteria in treated drinking water, bottled water, and purified water systems, enabling accurate recovery of stressed or chlorine-injured microorganisms.
Key Applications:
✔️ Heterotrophic Plate Count (HPC) per EPA 9215D & ISO 6222
✔️ Enumeration of oligotrophic bacteria in ultrapure water
✔️ Monitoring bacterial regrowth in distribution systems
✔️ Validation of water treatment efficacy
Scientifically Balanced Formula (Per Liter):
| Component | Quantity |
|——————————-|———-|
| Yeast Extract | 1.0 g |
| Acid Hydrolysate of Casein | 1.0 g |
| Glucose | 1.0 g |
| Soluble Starch | 1.0 g |
| Sodium Pyruvate | 0.6 g |
| K₂HPO₄ | 0.6 g |
| Pancreatic Digest of Casein | 0.5 g |
| Peptic Digest of Animal Tissue| 0.5 g |
| MgSO₄ (Anhydrous) | 0.048 g |
| Agar | 15.0 g |
Final pH: 7.2 ± 0.2 (25°C)
Critical Protocol Notes:
1️⃣ Dissolve 21.25g powder in 1L distilled water
2️⃣ Autoclave at 121°C for 15 minutes
3️⃣ Swirl vigorously post-sterilization to ensure homogeneous agar distribution
Technical Advantages:
– Dual recovery boosters: Sodium pyruvate + starch neutralize chlorine residuals
– Low nutrient profile: Prevents overgrowth of fastidious waterborne bacteria
– Enhanced clarity: Optimized for automated colony counting systems
– Extended stability: 3-year ambient shelf life
Compatibility:
– Validated for membrane filtration (MF) and pour plate methods
– Suitable for water samples with residual disinfectants
