Drop out medium
Drop out medium (DO-xxx)
To test for deficiency of strains, use a defined minimal medium (we use PMG) that is supplemented with all possible supplements, except the one you are testing for.
If available, use the premixed bottle which contains all ingredients, except nitrogen source and supplements (and agar if needed), which have to be added independently.
| Ingredient | Amount per liter |
|---|---|
| Potassium Hydrogen Phthallate | 3.0 g |
| Na2HPO4.2H2O (or anhydrous) | 2.76 g (2.2 g) |
| L-Glutamic acid monosodium salt hydrate
(or L-Glutamic acid) |
5.0 g (3.75 g) |
| D-Glucose | 20 g (=2% final concentration) |
| Salts Stock x50 | 20 ml |
| Vitamin Stock x1000 | 1.0 ml |
| Mineral Stock x10.000 | 0.1 ml |
When using L-Glutamic acid, set to pH 5.8 using NaOH 10N
In our lab we only work with 4 different deficiency markers so you only have to add these to the PMG: histidine, uracil, leucin, adenine.
Add these supplement each at 225mg/L
- histidine
- uracil
- leucin
Add adenine at 100mg/L
Label the bottle appropriately: for example 'PMG DO-ura' (when all supplements are added, except for uracil in this example).
For solid medium add 2% Agar-agar (20g/L)
