The selection of plasmids in yeast is based on the use of auxotrophic mutant strains, which cannot grow without a specific medium component (an amino acid, purine or pyrimidine). Transformation with a plasmid containing the mutated gene enables the transformant to grow on a medium lacking the required component. Although yeast can grow on a synthetic medium without any amino acids, better yield and growth rate can be achieved on richer media. Having a richer medium also increases the probability of successful transformations when screening libraries or performing gene knockouts. Composition of the media supplements is shown in Table 1 and is based on published formulations.1

Precautions and Disclaimer

This product is for R&D use only, not for drug, household, or other uses. Please consult the Safety Data Sheet for information regarding hazards and safe handling practices.

Preparation Instructions

Yeast Synthetic Drop-out Medium Supplement
(Table 2 shows the appropriate amount for each supplement)
1.39–1.92 g/L
Yeast nitrogen base without amino acids
(Product No. Y0626)
6.7 g/L
For plates add: Bacteriological agar
(Product No. A5306)
20 g/L

When preparing plates, autoclave for 15 minutes only; autoclaving longer will cause agar to become soft. Alternatively, the agar can be autoclaved separately from the Synthetic Drop-out Medium Supplement and a yeast nitrogen base.

After autoclaving add:

Glucose, 50% (w/v) solution 40 mL/L
(prepared from Product No. G7021, sterilized by 0.2 mm filtration)


Store media supplements desiccated at room temperature.

Table 1.
* Excluding dropped-out components
Table 2.


Growth test results of synthetic medium with relevant genotypes (Tables 3 and 4).

Table 3.+ = growth; - = no growth
Table 4.+ = growth; - = no growth


Kaiser C, Michaelis, S., Mitchel, A. 1994. Methods in Yeast Genetics, a Cold Spring Harbor Laboratory Manual , (Cold Spring Harbor, NY).