Modified acid medium (MAM)

Reference: Olaveson, Mary M. and Pamela M. Stokes. 1989. Responses of the acidophilic alga Euglena mutabilis (Euglenophyceae) to carbon enrichment at pH 3. Journal of Phycology. 25: 529-539.

Stock Substance Concentration Amount added to medium (mL/L)
1. (NH4)2SO4 50 g/L 10 mL
2. CaCl22H2O 1 g/L 10 mL
3. MgSO47H2O 50 g/L 10 mL
4. KH2PO4 30 g/L 10 mL
5. NaCl 3.0 g/L 10 mL
6. Na2EDTA2H2O 20 g/L 0.5 mL
7. Trace metal solution See below 1 mL
8. FeSO47H2O 4.98 g/L 1 mL
H2SO4 (concentrated) 1 mL/L
9. f/2 vitamin solution See below 1 mL

If adding agar, make medium double strength and adjust the pH to 3.5. Autoclave separately from agar. Add the agar to equivalent volume of purified water (for most purposes use 12 g/L) and autoclave. When cooled slightly, combine the two. This will prevent autolyzing of the agar at low pH (e.g. < 4.0).

Trace metal solution

Substance Concentration (g/L)
1.  H3BO3 2.86 g
2.  MnCl24H2O 1.81 g
3.  ZnSO47H2O 0.222 g
4.  Na2MoO42H2O 0.390 g
5.  CuSO45H2O 0.079 g
6.  Co(NO3)26H2O   0.0494 g

Dissolve each of the above substances separately prior to adding the next on the list.                                 

f/2 vitamin solution

Substock solutions:

First prepare separate substock solutions of cyanocobalamin (Vitamin B12) and biotin in purified water (e.g., Milli-Q, Nanopure, distilled water).

Substock Substance Concentration
1. Vitamin B12 (Cyanocobalamin) 10 mg/10 mL
2. Biotin 5 mg/50 mL

Working stock solution:

Then prepare the final working solution by combining the following amounts of the two substock solutions plus thiamine HCl to 100 mL of purified water.

Substance Concentration (per 100 mL)
1.  Vitamin B12 (Cyanocobalamin) 0.1 mL
2.  Biotin 1.0 mL
3.  Thiamine HCl 20 mg

Dispense the working solution as 1 mL aliquots in cryovials for convenient use when preparing the medium. Store the remainder of the primary stocks and working solution in polyethylene bottles. Wrap vials/bottles with Parafilm to avoid moisture loss and store all solutions frozen.

References: Guillard and Ryther 1962, Guillard 1975

Modified MAM for metal uptake experiments

Make as in the regular formulation but reduce levels of FeSO47H2O + H2SO4, Na2EDTA2H2O, and trace metal solution to 10% of the above levels.