SD Growth Medium w/o LEU-TRP

Principle and Interpretation

SD Growth Medium w/o LEU-TRP is a synthetic defined 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). SD Growth Medium w/o LEU-TRP includes a yeast nitrogen base along with ammonium sulfate, and dextrose as the carbon source, which is further supplemented with various amino acids except leucine and tryptophan which makes it a dropout growth medium for yeast cells. A leucine and tryptophan auxotrophic yeast mutant cannot grow on this media but a wild-type or a leucine and tryptophan prototrophic yeast strain can grow. The leucine and tryptophan auxotroph has a mutation in the genes (e.g. LEU2 TRPI) of the leucine and tryptophan synthesis pathway and this mutant strain will grow in this medium if leucine and tryptophan is supplied from outside e.g. from a plasmid which contains LEU2 and TRP1 gene (3). For this purpose, a leu2trp1 mutant strain of S. cerevisiae is transformed with a LEU2 and TRP1 containing plasmid and the transformants can be selected by growing the cells on SD Growth Media w/o LEU-TRP. Hence this medium is very useful in molecular genetics.