Malt MediumMalt Medium Suitable for all Prototheca cultures. Directions For 500 mL Total To 500 mL of dH2O add the following component. For 1. 5% agar medium add 7. 5 g of agar into the flask; do not mix. Cover and autoclave medium for no longer than 15 minutes to avoid caramelizing sugars. Store at refrigerator temperature. # Component Amount Stock Solution Concentration Final Concentration 1 Malt extract (Sigma M 0383) 33. 6 g 500 mL dH2O