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  1. Laboratory Methods (Food)

BAM Media M183: Dichloran rose bengal chloramphenicol (DRBC) agar

January 2001

Bacteriological Analytical Manual

Glucose 10.0 g
Bacteriological peptone 5.0 g
Potassium phosphate, monobasic 1.0 g
Magnesium sulfate heptahydrate 0.5 g
Rose Bengal
(5% soln., w/v)
0.5 ml
Dichloran (2,6-dichloro-4-nitroaniline) solution
(0.2%(w/v) in ethanol)
1.0 ml
Chloramphenicol 0.1 g
Distilled water 1 liter
Agar 15.0 g

Final pH should be 5.6. Mix ingredients, heat to dissolve agar and sterilize by autoclaving at 121°C for 15 min. Temper to 45 ± 1°C in a water bath and pour plates.


  1. DRBC agar is especially useful for analyzing sample containing "spreader" molds (e.g. Mucor, Rhizopus, etc.), since the added dichloran and rose bengal effectively slow down the growth of fast-growing fungi, thus readily allowing detection of other yeast and mold propagules, which have lower growth rates.
  2. Media containing rose bengal are light-sensitive;
    relatively short exposure to light will result in the formation of inhibitory compounds. Keep these media in a dark, cool place until used. DRBC agar should be used for spread plates only.

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

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