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Allen Medium

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Allen Medium

Modification of M.M. Allen's freshwater medium for blue-greens. Suitable for axenic and xenic cultures. The marine LB 1928 Spirulina platensis [Medium: Enriched Seawater (ES)] can be adapted to Allen medium (D. James 1982, pers. Comm.).


For 1 L Total

  1. To approximately 950 mL of dH2O add each of the components in the order specified while stirring continuously.
  2. Adjust pH to 7.8.
  3. Bring total volume to 1 L with dH2O.
    • For 1% agar medium: add 10 g of agar to the flask; do not mix.
  4. Cover and autoclave medium.
  5. Store at refrigerator temperature.

# Component Amount Stock Solution Concentration Final Concentration
1 HEPES buffer
(Sigma H-3375)
2.3 g/L 0.01 M
2 NaNO3
(Fisher BP360-500)
1.5 g/L 0.018 M
3 P-IV Metal Solution 1 mL/L
4 K2HPO4
(Sigma P 3786)
5 mL/L 1.5 g/200 mL dH2O 0.215 mM
5 MgSO47H2O
(Sigma 230391)
5 mL/L 1.5 g/200 mL dH2O 0.152 mM
6 Na2CO3
(Baker 3604)
5 mL/L 0.8 g/200 mL dH2O 0.19 mM
7 CaCl22H2O
(Sigma C-3881)
10 mL/L 0.5 g/200 mL dH2O 0.17 mM
8 Na2SiO39H2O
(Sigma 307815)
10 mL/L 1.16 g/200 mL dH2O 0.204 mM
9 Citric Acid•H2O
(Fisher A 104)
1 mL/L 1.2 g/200 mL dH2O 0.029 mM

Important Notes To Consider:

  • The quality of water, including natural seawater, is important. The term 'dH2O' generally refers to distilled, deionized, distilled/deionized water, Milli-Q water (Millipore Corp.), etc. Natural seawater and natural freshwater should be obtained from a non-polluted source.
  • When dissolving chemicals, wait for the first component to dissolve before adding the second. Stirring, and sometimes the addition of heat, is often required to dissolve the chemicals efficiently. Preparation of stock solutions for frequently made algal culture media make preparing media convenient but also necessary to avoid errors from weighing very tiny amounts.
  • Attention should be given to the pH of the final medium. In most cases, if pH adjustment is required, this occurs before sterilization. Please note that autoclaving removes carbon dioxide from media lacking carbonate stabilizing buffers. This would make the medium very alkaline soon after removal from the autoclave. In these cases, you should wait approximately 24 hours for gaseous equilibrium before inoculating the medium.