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STUDIES ON THE BINDING BETWEEN YEAST AND A MALT POLYSACCHARIDE THAT INDUCES HEAVY YEAST FLOCCULATION
Author(s) -
Herrera V. E.,
Axcell B. C.
Publication year - 1991
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1991.tb01077.x
Subject(s) - yeast , flocculation , polysaccharide , chemistry , biochemistry , chromatography , saccharomyces cerevisiae , polyacrylamide gel electrophoresis , gel electrophoresis , fermentation , husk , microbiology and biotechnology , biology , enzyme , botany , organic chemistry
A factor which causes heavy yeast flocculation of Saccharomyces cerevisiae 2036 was found to be associated with the malt husk by Axcell et al . 1 In the present work it was established that the factor is a polysaccharide and immunological techniques were used to show that the factor binds to the yeast cell surface during fermentation. It was shown that the factor is present at significantly higher concentrations in wort causing premature yeast flocculation than in normal wort. A particular malt husk extract, obtained using a mild aqueous extraction procedure, induced premature flocculation when added to fermentations in normal wort. In sodium‐dodecyl‐sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) of the malt husk extract, 4 protein bands (42,600; 17,500, 15,100 and 13,100 daltons) and a high MW (molecular weight) polysaccharide were identified. Antibodies were raised against electroeluted proteins as well as against the homogenized polyacrylamide gel containing the polysaccharide band. Enzyme‐linked immunosorbent assays (ELISA) showed that the protein components were present in similar concentrations in premature flocculent and normal wort. In contrast, the high MW polysaccharide occurred at a significantly higher concentration in wort inducing premature flocculation than in normal wort. Immunogold electron microscopy showed that the high MW polysaccharide bound extensively to the surface of flocculent cells grown in premature flocculent wort. There was markedly less labelling on yeast cells grown in normal wort. Negligible labelling occurred when the yeast cells were incubated with antibodies against the different protein components of malt husk extract.