GranuCult prime XLD Agar is a moderately selective and differential culture medium used for the isolation and differentiation of pathogenic Enterobacteriaceae, specifically Salmonella and Shigella species. It is designed for use in food, animal feed, water, and other materials.
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105287 GranuCult prime Xylose Lysine Deoxycholate (XLD) Agar, Merck
105287
Merck
Originally formulated by Taylor, Xylose Lysine Deoxycholate (XLD) Agar relies on three indicator systems to differentiate enteric pathogens. The medium contains three fermentable sugars (xylose, lactose, and sucrose). When these are fermented, acid is produced, causing the pH indicator (phenol red) to change from red to yellow. Shigella (which does not ferment xylose) and Salmonella (which exhausts xylose and then decarboxylates lysine to alkaline cadaverine) appear as red colonies. Additionally, the presence of sodium thiosulfate and ammonium iron(III) citrate allows for the detection of hydrogen sulfide (H₂S) production, resulting in colonies with black centers. The GranuCult® granular format ensures excellent solubility, minimal dust formation, and high reproducibility.
Advantages
- High Regulatory Compliance: Meets the specifications of EN ISO 6579, EN ISO 19250, APHA, and USDA-FSIS.
- Triple Differentiation: Detects carbohydrate fermentation, lysine decarboxylation, and H₂S production in a single plate.
- GranuCult® Technology: Superior flowability and wettability compared to traditional powders, reducing the risk of inhalation of hazardous dust.
- Selective Inhibition: Sodium deoxycholate effectively inhibits the growth of Gram-positive bacteria without overly suppressing delicate pathogens.
- Prime Quality Level: Designed for full regulatory compliance and rigorous quality control (Level 200).
Interpretation of Results
| Colony Appearance | Microorganism |
|---|---|
| Red colonies with black centers | Salmonella spp. (H₂S positive) |
| Red colonies without black centers | Shigella spp., H₂S-negative Salmonella |
| Yellow, opaque colonies | Escherichia coli, Klebsiella, Enterobacter |
| Yellow colonies with black centers | Citrobacter, Proteus (some strains) |
Technical specifications
| Catalogue number | 105287 |
| Product Line | GranuCult® prime |
| Compliance | ISO 6579, ISO 19250, APHA, USDA-FSIS |
| Typical Composition (g/L) | Yeast extract (3.0); NaCl (5.0); D(+)Xylose (3.75); Lactose (7.5); Sucrose (7.5); L(+)Lysine (5.0); Sodium thiosulfate (6.8); Ammonium iron(III) citrate (0.8); Phenol red (0.08); Sodium deoxycholate (1.0); Agar-agar (14.5) |
| pH (at 25 °C) | 7.4 ± 0.2 |
| Solubility | 55.0 g/L |
| Storage Temperature | 15 – 25 °C |
Available packaging options
| 1052870500 | 500 g plastic bottle |
| Brand | Merck |
