Synthetic Complete Supplement Mixture w/o LEU is used as a dropout supplement for all strains of Saccharomyces cerevisiae. It is composed of all the amino acids and uracil except leucine required for the vigorous growth of Saccharomyces cerevisiae. It can be mixed with yeast nitrogen base (YNB), ammonium sulphate and an appropriate carbon source (glucose/galactose/raffinose) to produce a media suitable for the growth of leucine prototrophs but not leucine auxotrophs