SD Growth Medium w/o TRP

Principle and Interpretation :

SD Growth Medium w/o TRP 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). SD Growth Medium w/o 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 tryptophan which makes it a dropout growth medium for yeast cells. A tryptophan auxotrophic yeast mutant cannot grow on this media but a wild-type or a tryptophan prototrophic yeast strain can grow. The tryptophan auxotroph has a mutation in a gene (e.g. TRP1) of the tryptophan synthesis pathway and this mutant strain will grow in this medium if tryptophan is supplied from outside e.g. from a plasmid which contains TRP1 gene (3). For this purpose, a trp1 mutant strain of S. cerevisiae is transformed with a TRP1 containing plasmid and the transformants can be selected by growing the cells on SD Growth Media w/o TRP. Hence this medium is very useful in molecular genetics.