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  1. Laboratory Methods (Food)

BAM Media M52: Buffered Listeria Enrichment Broth (BLEB)

Media Index for BAM

February 2013 Text revised, formulation is unchanged from previous (March 2006 version)

Media Base

Trypticase soy broth 30 g
Yeast extract 6 g
Monopotassium phosphate (anhydrous) 1.35 g/liter
Disodium phosphate (anhydrous) 9.6 g/liter
Sodium Pyruvate (Sodium salt) 1.11 g/liter
Distilled water 1 liter

Weigh ingredients and dissolve in water. Autoclave 15 min at 121°C. Final pH, 7.3 ± 0.1.

[Note: Optionally a filter-sterilized 10% (w/v) sodium pyruvate solution may be added after autoclaving (11.1ml/L)]

Selective Supplements

Acriflavin HCl 10 mg/liter
Nalidixic acid (sodium salt) 40 mg/liter
Cycloheximide 50 mg/liter

Prepare acriflavin and nalidixic acid supplements as 0.5% (w/v) stock solutions in distilled water. Prepare cycloheximide supplement as 1.0% (w/v) stock solution in 40% (v/v) solution of ethanol in water. Filter-sterilize stock solutions and store at 4°C, protect acriflavin from light.

Aseptically add the 3 selective supplements to enrichment after 4 h incubation at 30°C as described in Chapter 10. Final volume per supplement stock solution determined by total volume of BLEB used in enriched sample.

Original Source: Bacteriological Analytical Manual, 8th Edition, Revision A, 1998.

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