Introduction
Intended Use
For the isolation of Listeria spp. from food and environmental specimens.
Principle and Interpretation
Tryptone, proteose peptone, meat extract, yeast paste powder provide nitrogen sources, vitamins, amino acids, and growth factors; sodium chloride can maintain a balanced osmotic pressure; sodium dihydrogen phosphate and potassium dihydrogen phosphate as buffering agents; aesculin are fermentable sugars; lithium chloride and other antibiotics can inhibit Gram negative bacteria and most Gram positive bacteria.
Formulation
| Ingredients | /liter |
| Enzymatic Digest of Animal Tissues | 5.0g |
| Enzymatic Digest of Casein | 5.0g |
| Meat extract | 5.0g |
| Yeast extract | 5.0g |
| Sodium chloride | 20.0g |
| Disodium hydrogen phosphate dihydrate | 12.0g |
| Potassium dihydrogen phosphate | 1.35g |
| Aesculin | 1.0g |
| Lithium chloride | 3.0g |
| pH7.2±0.2 at 25°C | |
Preparation
Dissolve 57.4g in 1 litre of distilled water. Mix well and distribute into final containers. Sterilize by autoclaving at 121°C for 15 minutes. Then cool to 50°C，and add one Supplement(SR0120) per 225mL of base to prepare Half-Fraser Broth.
Quality Control
Cultural characteristics observed after incubation at 29-31°C for 22~26 hours
| Quality control strains | Growth | Characteristics |
| Listeria monocytogenes ATCC19115 | >20 cfu On PALCAM | Gray to black colony count with black halo |
| Escherichia coli ATCC25922 | < 100 colonies on TSA | Inhibition |
| Enterococcus faecalis ATCC29212 |
Storage and Shelf Life
2-30℃，Keep container tightly closed, avoid direct sunlight.
Use before expiry date on the label.
Precautions
1. When weighing the dehydrated medium, please wear masks to avoid causing respiratory system discomfort
2. Keep container tightly closed after using to prevent clumping.
Waste Disposal
Microbiological contamination was disposed by autoclaving at 121°C for 30 minutes.
