A+ Medium



A+ Medium Recipe

Directions 
For 1 L Total

Liquid media:
1. To approximately 900 mL of dH2O add the first 8 components in the order specified while stirring continuously.
2. Bring total volume to 1 L with dH2O.
3. Cover and autoclave medium.
4. Add filter sterilized A+ Trace Components.
5. Allow to cool then store at refrigerator temperature.

Agar media:
1. To approximately 390 mL of dH2O add the first 8 components in the order specified while stirring continuously.
2. Bring total volume to 500 mL with dH2O.
3. In a separate container add 15 g of agar to 500 mL of dH2O (final 1.5% w/v).
4. Cover and autoclave both solutions.
5. In a water bath allow both solutions to cool to 45-50 °C.
6. Add sterile Sodium Thiosulfate to agar solution and mix well.
7. Add filter sterilized A+ Trace Components.
8. Combine both agar and liquid solutions, mix well. Note the agar can solidify quickly.
9. Allow to cool then store at refrigerator temperature.

# Component Amount Stock Solution
Concentration
Final Concentration
1 NaCl (Fisher S271-500) 18 g/L   0.308 M
2 MgSO4·7H2O (Sigma 230391) 5 g/L   0.02 M
3 Na2EDTA·2H2O (Sigma ED255) 10 mL/L 0.3 g/100 mL 0.08 mM
4 KCl (Fisher P 217) 10 mL/L 6 g/100 mL 8.05 mM
5 CaCl2·2H2O (Sigma C-3881) 10 mL/L 3.7 g/100 mL 2.52 mM
6 NaNO3 (Fisher BP360-500) 10 mL/L 10 g/100 mL 11.8 mM
7 KH2PO4 (Sigma P 0662) 10 mL/L 0.5 g/100 mL 0.37 mM
8 Trizma Base pH 8.2 10 mL/L 10 g/100 mL 8.26 mM
9 A+ Trace Components (sterilize before adding) 10 mL/L    
10 Sodium Thiosulfate Pentahydrate (agar media only,sterile) (Baker 3946) 1 mL/L 24.819 g/100 mL 1 µM