UTEX sells Soil Extract + Sodium Metasilicate Medium at 1X concentration only. Stock solutions and individual components for this specific medium are currently not available for purchase.

Soil Extract + Sodium Metasilicate Medium

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Soil Extract + Sodium Metasilicate Medium

Modification of Soil Extract Medium for diatoms.


For 1 L Total
  1. Prepare 1 L of Bristol Medium and thoroughly mix.
  2. Discard 40 mL of the Bristol Medium.
  3. Add 40 mL of previously prepared GR+ Medium [Note: The GR+ should be filtered to remove soil particles].
    • For 1.5% agar medium add 15 g of agar into the flask; do not mix.
  4. Cover and autoclave medium.
  5. When cooled, add filter sterilized sodium metasilicate.
    • For agar medium, add sodium metasilicate, mix, and dispense before agar solidifies.
  6. Store at refrigerator temperature.

# Component Amount Stock Solution Concentration Final Concentration
1 Bristol Medium 960 mL
2 Soilwater: GR+ Medium 40 mL of supernatant
3 Sodium Metasilicate 1 mL 200 mM 200 µM

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.