Demi Fraser Broth
  Half Fraser Broth
EMD Cat. No. 1.00025.0500 / 5007
500 g, 5 kg


Medium for the selective and differential enrichment of Listeria from foods.

The medium complies with the recommendations of the Direction General de l’Alimentation (D.G.AL.) 1993 and ISO 11290-1 (2004).

Mode of Action Preparation
Experimental Procedure and Evaluation Quality Control
Typical Composition (g/liter) Literature
Additives  


Mode of Action
 Optimum growth conditions are created for Listeria due to the high nutrient content and the large buffer capacity. The growth of accompanying bacteria is largely inhibited by lithium chloride, nalidixic acid and acriflavine hydrochloride. The detection of the beta-D-glucosidase activity of Listeria is possible by the addition of esculin and ammonium iron(III) citrate (ferric ammonium citrate). The glucose esculin complex is cleaved by beta-D-glucosidase into esculetin and glucose. The esculetin then forms an olive-green to black complex with the iron(III) ions. Therefore, during the growth of Listeria in Fraser Broth, usually a blackening of the broth is observed.
Typical Composition (g/liter)
 Proteose peptone 5.0; peptone from casein 5.0; yeast extract 5.0; meat extract 5.0; sodium chloride 20.0; disodium phosphate 9.6; monopotassium phosphate 1.35; esculin 1.0; lithium chloride 3.0; Acriflavine hydrochloride 0.0125; Nalidixic acid 0.010.

Preparation
Suspend 55.0 g in 1 liter of purified water and autoclave (15 min at 121°C). If required dissolve the contents of 1 vial Ammonium Iron(III) Citrate (500mg) (contained in Fraser Supplement Cat. No. 1.10399.0001) with 1 ml of sterile distilled water and add to the broth after it has cooled to 50°C. Mix well.
pH: 7.2 ± at 25°C.
The prepared broth is yellowish-brown, and very slightly to slightly opalescent and may have slight precipitation.

Experimental Procedure and Evaluation
 Demi Fraser Broth is inoculated with sample material and incubated at 30°C for 24 ± 3 hours. Subculture onto OXFORD or PALCAM Agar or Full Fraser Listeria Enrichment Broth. To prepare Full Fraser Broth add 1 vial of antibiotic mixture (contained in Fraser supplement 1.10399.0001) to Demi Fraser Broth.
Quality control
Test strains
 		Inoculum
(cfu/ml)
 		Growth
(after 24 h at 307deg;C (cfu/ml))
 		Blackening
(after 48 h at 30°C)
Listeria monocytogenes ATCC 19111
 		10 - 100
 		> 1.0 x 104
 		+
Listeria monocytogenes ATCC 35152
 		10 - 100
 		> 1.0 x 104
 		+
Listeria monocytogenes ATCC 13932
 		10 - 100
 		> 1.0 x 104
 		+
Listeria innocua ATCC 33090
 		10 - 100
 		± 1.0 x 104
 		+
Enterococcus faecalis ATCC 19433
 		100 - 1000
 		± 1.0 x 103
 		-
Staphylococcus aureus ATCC 6538
 		100 - 1000
 		± 1.0 x 103
 		-
Escherichia coli ATCC 25922
 		100 - 1000
 		± 1.0 x 103
 		-
Additives
EMD Cat. No. Product Pack Size
1.00025.0500 Demi Fraser Broth (incl. antibiotics) 500 g
1.00025.5007 Demi Fraser Broth (incl. antibiotics) 5 kg
1.10398.0500 Listeria Enrichment Broth Base (Fraser) 500 g
1.10399.0001 Listeria Selective Supplement (Fraser) - Antibiotic mixture; - Ammonium Iron(III) Citrate 8 vials, 8 vials
1.07004.0500 Listeria Selective Agar Base (Oxford) 500 g
1.07006.0001 Listeria Selective Supplement (Oxford) 1 x 13 vials
1.11755.0500 Listeria PALCAM Selective Enrichment Broth Base 500 g
1.10823.0500 Listeria PALCAM Selective Enrichment Broth Base 500 g
1.12122.0001 Listeria PALCAM Selective Supplement 1 x 16 vials


Literature

Direction General de l'Alimentation: D.G.AL./SDHA/N93/No 8105 du 24-06- 1993.
ISO 11290-1: Microbiology of food and animal feeding stuffs - Horizontal method for the detection and enumeration of Listeria monocytogenes - Part 1: Detection method (2004).
FRASER, J.A., a. SPERBER, W.H.: Rapid detection of Listeria spp. in food and environmental samples by esculin hydrolysis. - J. Food Prot. 51; 762-765 (1988).



Listeria monocytogenes negative control, Staphylococcus aureus



© 2002 Merck KGaA, Darmstadt, Germany