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BAM Media M95: Mannitol-Egg Yolk-Polymyxin (MYP) Agar

January 2001

Bacteriological Analytical Manual

Mannitol-Egg Yolk-Polymyxin (MYP) Agar



Beef extract1 g
Peptone10 g
Mannitol10 g
NaCl10 g
Phenol red (1% solution in 95% ethanol)2.5 ml
Agar15 g
Distilled water900 ml


Heat with agitation to dissolve agar. Adjust pH so that value after sterilization is 7.2 ± 0.2. Dispense 225 ml portions to 500 ml Erlenmeyer flasks. Autoclave 15 min at 121°C. Cool to 50°C. MYP agar is commercially available from Difco.


Polymyxin B solution, 0.1%

Dissolve 500,000 units polymyxin B sulfate in 50 ml distilled water. Filter-sterilize and store in the dark at 4°C until needed.


Egg yolk emulsion, 50%

(see M51). Also available from commercial suppliers.


Final medium

To 225 ml melted base add 2.5 ml polymyxin B solution and 12.5 ml egg yolk emulsion. Mix and dispense 18 ml portions to sterile 15 x 100 mm petri dishes. Dry plates at room temperature for 24 h before use.


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