Product Overview
This MacConkey Agar Plate is a ready-to-use, selective and differential medium designed for the isolation, cultivation, and differentiation of enteric Gram-negative bacteria, including Escherichia coli, Salmonella, Enterobacter, and related species. The medium is based on the classical MacConkey formulation, which uses bile salts and crystal violet (as part of the selective system) to inhibit Gram-positive organisms while allowing Gram-negative enteric bacteria to grow.
The differential property comes from lactose and the pH indicator neutral red. Lactose-fermenting organisms, such as E. coli, produce acid that lowers the pH and causes the colonies and surrounding medium to appear pink to red, often with a bile precipitate halo. Non-lactose-fermenting organisms, such as Salmonella and Shigella, remain colorless or pale and do not produce a color change in the surrounding medium.
The 90mm format is suitable for streaking, swabbing, and general inoculation procedures, and the triple vacuum packaging allows safe transfer into controlled environments.
Intended Use
- Selective isolation and differentiation of enteric Gram-negative bacteria.
- Microbiological examination of pharmaceutical, food, and environmental samples.
- Hygiene monitoring and quality control testing.
- Educational and research laboratory use.
Composition (per Liter)
- Peptone: 20.0 g
- Lactose: 10.0 g
- Bile Salts: 5.0 g
- Sodium Chloride: 5.0 g
- Neutral Red: 0.03 g
- Agar: 14.0 g
- Final pH: 7.2 ± 0.2 at 25°C
Performance Characteristics
- Appearance: Red, smooth surface, free from cracks, visible impurities, and bubbles.
- Physicochemical: pH compliant; gel strength 500–650 g/cm².
- Sterility: No growth after incubation at 30–35°C for 2 days.
- Growth Promotion: Validated for typical colony characteristics and robust growth of Salmonella typhimurium, Enterobacter aerogenes, and Escherichia coli; Staphylococcus aureus is inhibited.
Interpretation of Results
- Pink to red colonies, often with a bile precipitate halo: Lactose fermenter (e.g., Escherichia coli).
- Colorless or pale colonies, no medium color change: Non-lactose fermenter (e.g., Salmonella, Shigella).
- No growth or very poor growth: Indicative of inhibition of Gram-positive organisms.
Packaging and Storage
- Format: 90mm × 10 plates per pack.
- Fill Volume: 20–25 mL per plate.
- Packaging: Three-layer vacuum packaging for controlled environment transfer.
- Shelf Life: 90 days from date of manufacture.
- Storage: Store at 2–8°C, protected from light. Do not freeze.
