ANTIGENIC STUDIES ON FLOCCULATING BREWERS-YEAST, SACCHAROMYCES-CEREVISIAE NCYC-227

Batch cultures of a brewer's strain of Saccharomyces cerevisiae, NCYC 227, in a defined medium exhibited characteristic flocculation during the late exponential phase of growth. However, early exponential cells were non-flocculent and flocculation of such cells could not be induced even in the presence of Ca2+. A specific glycoprotein, absent from the cell walls of non-flocculating exponentially growing cells of this yeast and those of non-flocculating strains of S. cerevisiae, was identified on the cell wall surface of flocculating exponentially growing cells of S. cerevisiae NCYC 227. Flocculent cells of S. cerevisiae NCYC 227 dispersed with EDTA and coated with monovalent Fab portions of the antibody showed reduced flocculation. Removal of the monovalent antibody portions from the cell surfaces induced cell flocculation in the presence of Ca2+. These results suggest a role for this glycoprotein in yeast cell flocculation.