Fraser Broth is designed as a secondary enrichment step following the use of Half Fraser Broth. It contains a rich base of Proteose Peptone, Tryptone, and Beef Extract, which provide essential nitrogen, vitamins, and amino acids. Yeast Extract further enhances growth by providing B-complex vitamins. High levels of Lithium Chloride, combined with the addition of selective antibiotics (Nalidixic Acid and Acriflavine), effectively inhibit the growth of competitive microflora, such as enterococci and Gram-negative bacteria. The medium also acts as a differential indicator: Listeria spp. hydrolyze Esculin to esculetin, which reacts with Ferric Ammonium Citrate (added separately) to produce a blackening of the broth, indicating a presumptive positive result.
Advantages
- ISO Standard Compliance: Formulated in accordance with ISO 11290 for the horizontal method for the detection and enumeration of Listeria.
- Dual-Action Selectivity: Uses both chemical (Lithium Chloride) and antibiotic agents to ensure high specificity for Listeria species.
- Visual Indicator: The blackening of the medium provides a clear, presumptive indication of Listeria presence during the enrichment phase.
- Optimized Recovery: Specifically balanced to support the growth of even small numbers of Listeria cells that have survived the primary enrichment phase.
- High Sensitivity: Capable of detecting Listeria monocytogenes in highly contaminated food and environmental matrices.
Technical specifications
| Catalogue number |
1182 |
| Brand |
Condalab |
| Application |
Secondary enrichment of Listeria monocytogenes (ISO 11290) |
| Typical Composition (g/L) |
Proteose Peptone (5.0); Tryptone (5.0); Beef Extract (5.0); Yeast Extract (5.0); Sodium Chloride (20.0); Lithium Chloride (3.0); Esculin (1.0); Disodium Phosphate (12.0); Monopotassium Phosphate (1.35) |
| Final pH (at 25 °C) |
7.2 ± 0.2 |
| Preparation |
57.4 g/L (Add Fraser + Ferric Citrate Supplements) |
| Storage Temperature |
2 – 25 °C |
Available packaging options
| 1182 |
500 g plastic bottle |
