Thermo Scientific™ Remel™ Demi-Fraser Broth Base

Description

Demi-Fraser Broth Base (Dehydrated) is recommended for use in qualitative procedures for the selective isolation and cultivation of Listeria monocytogenes.

Selectively isolate and cultivate Listeria monocytogenes from food and environmental samples using Thermo Scientific™ Remel™ Demi-Fraser Broth Base (Dehydrated).

Demi-Fraser Broth Base is a modification of Fraser Broth Base developed by Fraser and Sperber and used for rapid detection of Listeria in food and environmental samples¹. The nalidixic acid and acriflavine concentrations in this medium have been reduced to 10 mg/L and 12.5 mg/L respectively in accordance with L'association française de normalisation (AFNOR) guidelines².

Listeria monocytogenes is a common contaminant in raw milk, meats, vegetables, seafood and in the food processing environment^3,4. Isolation of Listeria species presents a grave challenge because it can grow in pH environments ranging from 5.0 – 9.6 and even under refrigeration.

Successful recovery of Listeria from food and environmental sources requires a medium which can promote the growth of potentially injured cells while inhibiting the growth of non-Listeria background organisms. The isolation of low numbers of L. monocytogenes can be improved by enrichment procedures using a broth medium.

• Selective Medium: Contains lithium chloride, nalidixic acid and acriflavine
  Lithium chloride – inhibits most enterococci which can also hydrolyse esculin.
  Nalidixic acid – blocks DNA replication of susceptible bacteria.
  Acriflavine – inhibits growth of secondary gram-positive microflora.
• Easy-to-interpret: Color change on visual inspection - blackening of the solution
• Conforms to L’association française de normalisation (AFNOR) guidelines

Demi-Fraser Broth Base contains casein peptone, meat peptone and beef extract that provide essential amino acids, peptides, and nitrogen necessary for growth of Listeria species. Yeast extract supplies B-complex vitamins, sodium chloride provides essential electrolytes and maintains osmotic equilibrium. Disodium phosphate and monosodium phosphate act as buffers and maintain the pH. Lithium chloride, nalidixic acid, and acriflavine act as selective agents. 0.1 mL of Fraser Broth Additive (REF R450361) is added to every 10 mL of prepared Demi-Fraser Broth Base immediately before use. This supplies the ferric ions in form of ferric ammonium citrate. All Listeria species hydrolyse esculin to form 6,7-dihydroxycoumarin, which combines with ferric ions to blacken the medium.

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Specifications

• Description: Demi-Fraser Broth Base
• Form: Powder
• Product Type: Dehydrated Culture Media
• Quantity: 500 g

Safety and Handling

SDS

For Laboratory Use Only