Yeast Nitrogen base without Amino acids, without Ammonium sulphate and without ZincZinc sulphate, ZnSO4. 7H20 is omitted from this formulation of Yeast Nitrogen base without Amino acids to provide the researcher the possibility to grow yeast cells in the absence of Zinc or to replace this element. Ammonium sulphate, as a source of Nitrogen, has been omitted to test the ability of yeast cells to assimilate different nitrogen sources like Potassium nitrate. Suspend 1. 9 gram powdered medium in 1 litre distilled water Store dry at room