Media formula

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TAP (Tris-Acetate Phosphate)

To make one liter of TAP:

  • 10 mL 2M Tris-acetate (pH 7.0)
  • 10 mL Phosphate buffer (pH 7.0)
  • 10 mL nutrient stock
  • 10 mL trace metals (10x dilution)
  • Bring to 1 liter with distilled water


  • For plates add 15g agar per liter (1.5%)
  • For TAP-sulfur substitute MgCl2 for the MgSO4 in the nutrient stock and omit trace metals


2M Tris-acetate stock

  • 242 g Tris base
  • Dissolve in 600 mL water while titrating to pH 7.0 with glacial acetic acid.
  • Bring to 1 liter

Phosphate buffer

  • 10.8 g K2HPO4
  • 5.6 g KH2PO4
  • Bring to 1 liter

Nutrient stock

  • 40 g NH4Cl
  • 10 g MgSO4·7H2O
  • 5 g CaCl2·2H2O
  • Bring to 1 liter

Trace metals

Making this is a complex proceedure so (unless you think you will be using a lot of it) there are a couple of alternatives.

  • Make a soil extract by shaking a few grams of soil in water
  • Use a small amount of Job's plant food spike
  • Use tap water rather than distilled.

This makes a liter of full-strength, enough for 1000 L of TAP. Dilute an aliquot tenfold and use the diluted stock in making TAP

  1. Dissolve 50g of acid free EDTA in 250 ml of ddH2O. Heat to dissolve.
  2. Dissolve the following, one by one, in order, heating to approximately 100° in 550 ml ddH2O.
    • 11.40 g BO3H3
    • 22.00 g ZnSO4·7H2O
    • 5.06 g MnCl2·4H2O
    • 4.99 g FeSO4·7H2O
    • 1.61 g CoCl2·6H2O
    • 1.57 g CuSO4·5H2O
    • 1.1 g Mo7O24(NH4)6·4H2O (Ammonium Molybdate)
  3. Mix the two solutions (1 & 2) together. The resulting solution should be blue-green.
  4. Heat to 100°C. Cool slightly, but don't let the temperature drop below 80°-90°.
  5. Adjust pH to 6.5 to 6.8 with 20% KOH (approximately 83 ml). Don't let the temperature drop below 70° until after the pH is adjusted.
  6. Make up to 1L and let stand in a 2L Erlenmeyer flask, stoppered loosly. The color should change from green to purple over a period of days.
  7. Remove the rust-coloured precipitate by filtering, with suction, through 3 layers of Whatman #1 filter paper in a Buchner funnel. Repeat until no more precipitate is seen on the filter paper
  8. Store in a brown bottle at 4°.


Recipe taken from: