SDA Growth Medium w/o LEU-TRP-URA

Principle and Interpretation

SDA Growth Medium w/o LEU-TRP-URA is a synthetic defined agar media for the selective growth of Saccharomyces cerevisiae. Synthetically Defined media known as Yeast Nitrogen Base Media for the growth of yeast cells were first cited by Wickerham (1, 2). Synthetic defined Growth Medium w/o LEU-TRP-URA includes a yeast nitrogen base along with ammonium sulfate and dextrose as the carbon source, which is further supplemented with various nutrients except leucine, tryptophan and uracil. This makes it a triple dropout growth medium for yeast cells. A leucine, tryptophan and uracil auxotrophic yeast mutant strain cannot grow on this media but a wild-type or a leucine, tryptophan and uracil prototrophic yeast strain can grow. The leucine, tryptophan and uracil auxotroph has mutation in the genes (e.g. LEU2, TRP1 and URA3) of the leucine, tryptophan as well as uracil synthesis pathway and this mutant strain will grow in this medium if leucine, tryptophan and uracil are supplied from outside e.g. from plasmids which contain LEU2, TRP1, URA3 gene (3). For this purpose, a leu2trplura3 mutant strain of S. cerevisiae is transformed with LEU2, TRP1 and URA3 containing plasmid and the transformants can be selected by growing the cells on SD Growth Medium w/o LEU-TRP-URA.