Yeast Nitrogen Base (YNB) media have been prepared according the formulae of Wickerham (1943-51) and Burkholder (1943). YNB is a well defined composition of salts, vitamins, amino acids and a nitrogen source for a vigorous growth of Sacharomyces cerevisiae., Y2030 has the same formulation as YNB without Amino Acids except that ammonium sulfate as a source of nitrogen has been omitted to test the ability of yeast cells to assimilate different nitrogen sources (i.e. Potassium Nitrate). Application: For carbon assimilation tests in the characterization and identification of yeasts. , Note: The addition of a carbon source like glucose, galactose or raffinose is required.