The medium utilizes Tributyrin (glyceryl tributyrate), a simple triglyceride, as the lipid substrate. Lipolytic organisms secrete the enzyme lipase, which hydrolyzes tributyrin into glycerol and fatty acids. Because tributyrin forms an opaque emulsion in the agar, its hydrolysis results in a distinct clear zone (halo) around the colonies of lipolytic organisms. As part of the NutriSelect® Plus line, this medium is manufactured to high-quality standards, ensuring a stable emulsion and clear, reproducible results for the detection of spoilage organisms in fatty foods.
Advantages
- Clear Differentiation: Provides a sharp visual contrast between lipolytic (clear zone) and non-lipolytic (opaque background) organisms.
- High Sensitivity: Tributyrin is a relatively small molecule that is easily hydrolyzed by a wide range of microbial lipases.
- NutriSelect® Plus Quality: Premium-grade ingredients ensure a uniform emulsion and consistent performance across different batches.
- Versatile Detection: Suitable for the detection of lipolytic bacteria (e.g., Pseudomonas, Staphylococcus) and various lipolytic yeasts and molds.
- Standardized Testing: Widely used in the dairy industry to screen for organisms that cause rancidity in butter and milk products.
Interpretation of Results
| Reaction |
Appearance |
Interpretation |
| Positive (+) |
Clear zone around the colony |
Lipolytic activity (Lipase produced) |
| Negative (-) |
No clear zone; medium remains opaque |
No lipolytic activity |
Technical specifications
| Catalogue number |
91015 |
| Brand / Product Line |
Sigma-Aldrich / NutriSelect® Plus |
| Typical Composition (g/L) |
Peptone (5.0); Yeast extract (3.0); Tributyrin (10.0); Agar (15.0) |
| pH (at 25 °C) |
7.5 ± 0.2 |
| Preparation |
23.0 g/L |
| Storage Temperature |
15 – 25 °C |
Available packaging options
| 91015-100G |
100 g plastic bottle |
| 91015-500G |
500 g plastic bottle |
