|
| Monopotassium phosphate (anhydrous) |
1.35 g/liter |
| Disodium phosphate (anhydrous) |
9.6 g/liter |
| Acriflavin HCl | 10 mg/liter |
| Nalidixic acid (sodium salt) |
40 mg/liter |
| Cycloheximide | 50 mg/liter |
| Pyruvic acid (Sodium salt) (Sigma), 10% (w/v) aqueous solution |
11.1 ml/liter |
Sterilize enrichment broth without the 3 selective agents by autoclaving at 121°C for 15 min. Then add 2.5 ml 10% (w/v) filter-sterilized sodium pyruvate. [Note: Sodium pyruvate may also be added before autoclaving.] Add the 3 selective ingredients aseptically to 225 ml enrichment broth plus the 25 g food sample after 4 h incubation at 30°C. Prepare acriflavin and nalidixic supplements as 0.5% (w/v) stock solutions in distilled water. Prepare cycloheximide supplement as 1.0% (w/v) stock solution in 40% (v/v) solution of ethanol in water.
Filter-sterilize the three selective ingredients. Add stock solutions: 0.455 ml acriflavin, 1.8 ml sodium nalidixate, and 1.15 ml cycloheximide to 225 ml enrichment broth plus the 25 g food sample.
Note: For information on cycloheximide availability problems, see Advisory for BAM Users on Reported Supply Problems for Cycloheximide.
Hypertext Source: Bacteriological Analytical
Manual, 8th Edition, Revision A, 1998.
(Revised SEP-26-2000)
