|Yeast extract||10.0 g|
|Ammonium acetate||1.5 g|
|Distilled water||1 liter|
Dissolve ingredients and adjust to pH 7.5 ± 0.1, using 2 M sodium carbonate. Dispense 15 ml into 20 × 150-mm screw-cap tubes and sterilize by autoclaving for 15 min at 121°C.
After sterilization, add 0.6 ml of sterilized 10% raffinose and 0.2 ml each of filter-sterilized 0.66 M sodium carbonate and 0.32% cobalt chloride (CoCl2·6H2O) dropwise to each tube.
Check pH of one or two tubes; it should be 7.8 ± 0.1. Just before use, steam medium for 10 min; after cooling, add 0.2 ml of filter-sterilized 1.5% sodium ascorbate (prepared daily) to each tube.
Original Source: Bacteriological Analytical Manual, 8th Edition, Revision A, 1998.