SDP + URA + 5-FOA Medium

• 1. Dissolve 1.7 g of yeast nitrogen base without ammonium sulfate and without amino acids, 1 g of L-proline, ≥25 mg of 5-fluoroortic acid (5-FOA), 10 mg of uracil, and 20 g of dextrose in 100 mL of dH₂O. Heat to 65°C to dissolve all components. Adjust the pH to 3.5–4. Filter-sterilize.

  • The use of proline as the sole nitrogen source (in place of ammonium sulfate), together with lower amounts of uracil, allows much lower concentrations of 5-FOA to be used. However, not all genetic backgrounds are sensitive to SDP + URA + 5-FOA medium and the addition of some nutritional supplements abolishes sensitivity to 5-FOA (McCusker and Davis 1991).

• 2. Add 20 g of Bacto agar to 900 mL of dH₂O, and autoclave in a 2-L flask.

• 3. Add the filter-sterilized solution to the autoclaved agar, mix thoroughly, and pour the medium into Petri dishes.

  • This recipe is adapted from McCusker and Davis (1991).

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