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U.S. Department of Health and Human Services


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Bacteriological Analytical Manual (BAM) Media M98: Modified Cellobiose-Polymyxin B-Colistin (mCPC) Agar

January 2001

 Solution 1

Peptone10 g
Beef extract5 g
NaCl20 g
1000X Dye stock solution*1 ml
Agar15 g
Distilled water900 ml


Adjust to pH 7.6. Boil to dissolve agar. Cool to 48-55°C.


*1000X Dye stock solution

Bromthymol blue4.0 g
Cresol red4.0 g
Ethanol, 95%100 ml

For consistent medium color, use dye solution rather than repeatedly weighing out dry dyes. Dissolve dyes in ethanol for 4% (w/v) stock solution. Using 1 ml of this solution per liter of mCPC agar gives 40 mg bromthymol blue and 40 mg cresol red per liter.



Solution 2

Cellobiose10 g
Colistin400,000 units
Polymyxin B100,000 units
Distilled water100 ml


Dissolve cellobiose in distilled water by heating gently. Cool. Add antibiotics.


Add Solution 2 to cooled Solution 1, mix, and dispense into petri dishes. Final color, dark green to green-brown.

NOTE: This medium, like TCBS, is very inhibitory and does not require autoclaving. Medium may be stored 2 weeks at refrigeration temperatures.

Storage:limit: 2 wksTemperature: 4°C


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