Spirit Blue Agar (NutriSelect Plus) contains Spirit Blue as a pH indicator and as a complexing agent with lipids. The medium is designed to be used with a lipid source, such as Lipase Reagent or Olive Oil. When microorganisms produce lipase, they hydrolyze the lipids in the medium, resulting in the formation of clear zones around the colonies. Additionally, the hydrolysis of the fat lowers the pH, causing the Spirit Blue indicator to change from a pale blue to a deep blue color. As part of the NutriSelect® Plus line, this medium ensures premium quality and consistent emulsification for reliable lipolysis testing.
Advantages
- Clear Visualization: Provides two indicators of lipolysis—a distinct clear zone and a deepening of the blue color around the colony.
- High Sensitivity: Optimized for the detection of even weak lipolytic activity in food spoilage organisms like Pseudomonas and Staphylococcus.
- NutriSelect® Plus Quality: Manufactured with high-purity ingredients to ensure stable emulsion and sharp color transitions.
- Nutrient Rich: Casein peptone and yeast extract provide essential nitrogen, vitamins, and minerals for the growth of a wide range of organisms.
- Standardized Testing: Follows traditional methods for screening lipolytic contaminants in the dairy and fats/oils industries.
Interpretation of Results
| Reaction |
Appearance |
Interpretation |
| Positive (+) |
Deep blue colonies often surrounded by a clear zone |
Lipase production (Lipolysis) |
| Negative (-) |
Pale blue/colorless colonies; medium remains opaque blue |
No lipolytic activity |
Technical specifications
| Catalogue number |
S4306 |
| Brand / Product Line |
Sigma-Aldrich / NutriSelect® Plus |
| Typical Composition (g/L) |
Casein peptone (10.0); Yeast extract (5.0); Spirit Blue (0.15); Agar (20.0) |
| pH (at 25 °C) |
6.8 ± 0.2 |
| Preparation |
35.0 g/L |
| Storage Temperature |
15 – 25 °C |
Available packaging options
| S4306-500G |
500 g plastic bottle |
