Paragraph 3 Culture medium
Bacterial count. The medium to be used shall be yeastrel milk agar, either compounded in the laboratory or prepared in accordance with the manufacturer’s directions from a granular desiccated medium and shall have the following composition:—
| Yeastrel | 3.0 grams |
| Peptone | 5.0 grams |
| Agar | 15.0 grams |
| Milk (fresh or spray-dried, skim or whole milk) | 10.0 ml. |
| Distilled water | to 1 litre |
Where the medium is compounded in the laboratory it shall be filtered through a pulp-paper filter.
The medium shall be sterilised either by autoclaving at 121degC. for 20 minutes or in a steamer for 30 minutes on three successive days.
The final reaction of the medium at room temperature shall be pH 7.2.