Adaptation of E.G. Pringsheim's biphasic soil-water medium. Variations of this medium are suitable for xenic cultures, especially for isolation purposes and for growing algae to secure "normal" growth forms. Soilwater is not a well-defined medium, yet not all soil is suitable for culturing a broad range of algae. UTEX utilizes soil that was obtained in the early 1970s as greenhouse soil from Indiana University. For a long shelf life it must be kept dry and away from light. UTEX keeps it in sealed 5-gallon plastic containers. There is almost certainly nothing special about the particular soil used by UTEX. However, several considerations are probably important, including the following:
Prior to its use in soil-water media, treat soil in batches by placing it in a heat-resistant pan lined with aluminum foil, fill the soil to a so depth of ¼ inch, and bake at 150 °C for 2 hours. After it cools, cover the pan with aluminum foil and store in darkness at room temperature. Avoid excessive moisture during storage.
UTEX only sells complete media at 1X concentration. Stock solutions and individual components are currently not available for purchase.