SDA Growth Medium w/o URA

Principle and Interpretation

SDA Growth Medium w/o 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). SDA Growth Medium w/o URA includes a yeast nitrogen base along with ammonium sulfate, and dextrose as the carbon source, which is further supplemented with various amino acids except uracil which makes it a dropout growth medium for yeast cells. A uracil auxotrophic yeast mutant cannot grow on this media but a wild-type or a uracil prototrophic yeast strain can grow. The uracil auxotroph has a mutation in a gene (e.g. URA3) of the uracil synthesis pathway and this mutant strain will grow in this medium if uracil is supplied from outside e.g. from a plasmid which contains URA3gene (3). For this purpose, an ura3 mutant strain of S. cerevisiae is transformed with an URA3 containing plasmid and the transformants can be selected by growing the cells on SDA Growth Media w/o URA. Hence this medium is very useful in molecular genetics.