FLOCCULATION OF BREWER'S YEAST

Abstract

Analyses of cell walls isolated from flocculent and non-flocculent strains of Saccharomyces cerevisiae revealed no appreciable differences in the levels of major components. Fractionation using ethylenediamine according to the method of Korn & Northcote furnished a Fraction A from flocculent walls which had higher levels of phosphorus than that from non-flocculent. 70% of the phosphorus of this fraction was incorporated as phosphodiester in a manno-protein. Walls from flocculent yeasts bound on average twice as much calcium as did walls from non-flocculent yeasts. Removal of the phosphorylated manno-protein decreased the capacity of the cell wall to bind calcium and rendered the wall non-flocculent, emphasizing the role of superficial phosphate groups in flocculation.