Paragraph 3 Culture medium
Coliform test. The medium to be used shall be bile salt lactose broth, 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:—
| Peptone | 20.0 grams |
| Bile salts | 5.0 grams |
| Sodium chloride (A.R.) | 5.0 grams |
| Lactose (A.R.) | 10.0 grams |
| Distilled water | to 1 litre |
| Brom-cresol purple (1.6%) | 2.5 ml. |
The medium shall be tubed in 5 ml. quantities in 150 x 16 mm. tubes provided with a rimless Durham tube (50 x 6.5 mm.) and sterilised either by autoclaving at 121degC. for 15 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.