Emerson YSS Agar is recommended for the isolation of Actinomycetes and other fungi. Emerson YSS (Yeast Soluble Starch) Agar has yeast extract that serves as a source of B-complex vitamins, amino acids and essential nutrients. Soluble starch serves as a source of energy and carbon. It also neutralizes the toxic metabolites formed. Phosphates buffer the medium whereas magnesiumnsulphate acts as a source of ions and sulphates.