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Specifications:
| Application | Microbiology | ||
| Storage Temperature | 2-8°C | ||
| Product Type | Culture Medium | Forms | Liquid |
| Product Brand | Liofilchem | ||
| Product Grade | Microbiology grade | ||
Selective and Differential Medium for the Isolation of Enterobacteriaceae and Other Gram-Negative Bacilli
MacConkey Agar by Liofilchem® is a slightly selective and differential culture medium designed for the isolation, cultivation, and differentiation of Gram-negative enteric bacilli, particularly from clinical samples, pharmaceutical products, food, wastewater, and other materials of sanitary importance. The medium is formulated in accordance with USP/EP/JP harmonized methods for the detection of Escherichia coli in non-sterile pharmaceutical products.
This medium supports clear differentiation between lactose-fermenting organisms, which appear as pink colonies, and non-lactose fermenters, which produce colorless or transparent colonies. It is widely used in clinical and industrial microbiology as a frontline medium for identifying members of the Enterobacteriaceae family.
Intended Use
- Isolation and presumptive identification of Enterobacteriaceae and other Gram-negative organisms.
- Differentiation of lactose fermenters (e.g., E. coli, Klebsiella spp.) from non-fermenters (e.g., Salmonella, Shigella, Proteus spp.).
- Recommended in harmonized pharmacopeial methods (USP/EP/JP) for E. coli detection in non-sterile products.
Typical Composition (per Liter)
| Component | Concentration (g/L) |
|---|---|
| Pancreatic Digest of Gelatin | 17.0 |
| Peptone from Meat | 1.5 |
| Peptone from Casein | 1.5 |
| Lactose | 10.0 |
| Sodium Chloride | 5.0 |
| Bile Salts | 1.5 |
| Agar | 15.0* |
| Neutral Red (pH Indicator) | 0.03 |
| Crystal Violet (Selective Agent) | 0.001 |
| Final pH (at 25°C) | 7.1 ± 0.2 |
*Agar content adjusted based on gel strength to meet performance specifications.
Principle of the Method
- Lactose fermentation lowers pH, causing neutral red to stain colonies pink/red.
- Bile salts and crystal violet inhibit Gram-positive organisms, promoting Gram-negative selectivity.
- Peptones and digests provide essential nutrients for bacterial growth.
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Differentiation is based on colony color:
- Lactose fermenters: Pink to red colonies, often with bile precipitation.
- Non-lactose fermenters: Colorless or translucent colonies.
Performance Characteristics
| Organism (ATCC®) | Colony Appearance |
|---|---|
| Escherichia coli ATCC® 8739 | Pink colonies with bile precipitate |
| Klebsiella pneumoniae ATCC® 13883 | Pink colonies |
| Salmonella Typhimurium ATCC® 14028 | Colorless colonies |
| Shigella flexneri ATCC® 12022 | Colorless colonies |
| Proteus mirabilis ATCC® 12453 | Colorless colonies |
| Enterococcus faecalis ATCC® 29212 | Small, opaque colonies (inhibited/poor growth) |
| Staphylococcus aureus ATCC® 25923 | Inhibited |
Productivity Ratio (PR) ≥ 0.5 indicates acceptable performance.
Test Procedure
- Inoculate the surface of the agar by streaking or spreading the specimen directly or from enrichment broth.
- Incubate aerobically at 35 ± 2°C for 18–24 hours.
- For E. coli detection in pharmaceuticals, follow USP/EP/JP harmonized methods with pre-enrichment in Tryptic Soy Broth and MacConkey Broth before plating.
Storage & Shelf Life
| Product Type | Storage Conditions | Shelf Life |
|---|---|---|
| Dehydrated Medium | 10–30°C (dry, sealed) | 4 years |
| Ready-to-Use Bottles | 10–25°C, protect from light | 2 years |
| Ready-to-Use Plates | 10–25°C, protect from light | 6 months |
Available Formats
| Format | Packaging | Ref. Code |
|---|---|---|
| 90 mm Ready-to-Use Plates (20) | 2 × 10 plates | 10029 |
| 90 mm Ready-to-Use Plates (100) | 10 × 10 plates | 10029* |
| 100 mL Bottles | 6 × 100 mL | 402240 |
| 200 mL Bottles | 6 × 200 mL | 412240 |
| 500 mL Bottles | 6 × 500 mL | 470090 |
| Dehydrated Medium (100 g) | 1 bottle | 620028 |
| Dehydrated Medium (500 g) | 1 bottle | 610028 |
| Dehydrated Medium (5 kg) | 1 drum | 6100285 |
🚫 Warnings and Precautions
- For in vitro diagnostic use (IVD) only
- For laboratory professional use
- Do not use if packaging is damaged or past expiry
- Always consult the SDS and follow proper biosafety procedures
- Not intended as a standalone diagnostic tool—confirmatory testing required
Liofilchem® MacConkey Agar is a trusted, pharmacopeia-compliant medium for the isolation and differentiation of Gram-negative enteric bacteria. Its reliable performance and compliance with international standards make it ideal for clinical diagnostics, pharmaceutical quality control, and food and environmental microbiology.
- Pack Size: 6 x 100 mL 6 x 500 mL 6 x 200 mL