Complete Supplement Mixture w/o HIS-TRP is used as a dropout supplement for all strains of Saccharomyces cerevisiae. It is composed of all the amino acids and uracil except histidine and tryptophan. 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 histidine and tryptophan prototrophs but not histidine and tryptophan auxotrophs