microbiological medium ingredient, derived from extracts of microbial organisms yeast extract From BD Bionutrients Technical Manual (3rd edition revised): Bacto™ Yeast Extract is one of the most complete and versatile fermentation bionutrients available. It is an important ingredient for the microbiological assay of vitamins. Yeast extract is also of value in the assay of antibiotics. B factor, a growth substance necessary for the production of rifampin in a Nocardia sp., can be isolated from yeast extract Ash content is 11.2% NaCl content is 0.1% From www.SigmaAldrich.com: A water soluble extract of autolyzed yeast cells. Yeast extract is a mixture of amino acids, peptides, water soluble vitamins and carbohydrates and can be used as additive for culture media. A water-soluble extract of autolyzed yeast (Saccharomyces cerevisiae), used for the culturing of microorganisms. Yeastrel Yeast extrakt Carrine Blank