Yeast Selective Media and Agar

Materials

• Minimal SD Base (Clontech 630411)
• Dropout Supplement (as an example -Leu DO supplement has all the nutrients except leucine)
• Bacto Agar (if making plates)

Selective yeast media is made so that a particular amino acid or nutrient (typically Leu, Trp, Ura, His or Ade) is missing and must be provided by the yeast strain. Therefore a yeast strain which is auxotrophic for that nutrient can only grow on that selective media if a selective plasmid is provided. See [Wikipedia Article on Auxotrophy]. As an example, BY4742 is auxotrophic for Leu, Lys, His and Ura. Therefore this strain cannot grow on -Leu plates, unless transformed with a plasmid containing the LEU2 gene. In this way transformants can be selected.

Preparation

• Weigh out 2.67g/100 mL of Minimal SD Base and 0.069g/100mL of the appropriate dropout supplement.
• If making plates, add 2g/100mL of bacto-agar
• Stir to dissolve and check that pH is at 5.8
• Autoclave for 20 min at 121C using the liquid cycle
• Unless adding adenine hemisulfate, there is no need to let the media cool, so plates can be poured immediately.
• Pour plates, let dry and store in the cold room