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U.S. Department of Health and Human Services


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Bacteriological Analytical Manual (BAM) Media M52: Buffered Listeria Enrichment Broth (BLEB)

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

Media Base:

Trypticase soy broth30 g
Yeast extract6 g
Monopotassium phosphate
1.35 g/liter
Disodium phosphate
9.6 g/liter
Sodium Pyruvate
(Sodium salt)
1.11 g/liter
Distilled water1 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 HCl10 mg/liter
Nalidixic acid
(sodium salt)
40 mg/liter
Cycloheximide50 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.