7H9 (and its solid counterpart, 7H10 agar) are selective media used for the culture of free-living mycobacteria such as M. tuberculosis and M. smegmatis.
(makes 1L medium)
- Deionized water
- 4.7g Middlebrook 7H9 powder (DifCo catalog # 0713-01-7)
- 5mL 10% Tween-80: Dilute 40g Tween-80 (liquid) into final volume 200mL with deionized water. Stir on low heat (~65°C) until completely dissolved (may take ~15 minutes). Filter sterilize with a 0.22μm filter. Store at 4°C wrapped in aluminum foil, as Tween is light sensitive.
For M. tuberculosis:
- 100mL OADC (Dubos/Middlebrook Oleic Acid Albumin Dextrose Complex)
- 10mL 50% glycerol
- (If you are using lung homogenates or the like) 10mL 10mg/mL cyclohexamide
For M. smegmatis:
- 100mL ADS (Albumin-Dextrose-Saline): 8.1g NaCl, 50g Bovine Serum Albumin Fraction V, 20g anhydrous dextrose in 1L deionized water. Filter sterilize in a 0.22μm filter, and store at 4°C.
- Dissolve 4.7g Middlebrook 7H9 poweder in 900mL deionized water. Mix with a magnetic stir bar until soluble components have dissolved.
- Add the rest of the ingredients appropriate for the organism at hand and continue stirring until well mixed.
- Sterilize by filtration through a 0.22μm pore membrane. Store at 4°C.