Bacteriological Analytical Manual
|Bacteriological peptone||5.0 g|
|Potassium phosphate, monobasic||1.0 g|
|Magnesium sulfate heptahydrate||0.5 g|
(5% soln., w/v)
|Dichloran (2,6-dichloro-4-nitroaniline) solution|
(0.2%(w/v) in ethanol)
|Distilled water||1 liter|
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.
- 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.
- 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.