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Pb 2+ Inhibits Competitively Flocculation of Saccharomyces cerevisiae
Author(s) -
Gouveia Cláudia,
Soares Eduardo V.
Publication year - 2004
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.2050-0416.2004.tb00193.x
Subject(s) - flocculation , saccharomyces cerevisiae , yeast , chemistry , lectin , calcium , biochemistry , ion , biophysics , microbiology and biotechnology , chromatography , biology , organic chemistry
Pb 2+ inhibited calcium‐induced flocculation in Flo1 (S646–1B) and NewFlo phenotype strains (NCYC 1190, NCYC 1195 and NCYC 1364) of Saccharomyces cerevisiae. Flocculation was restored after washing with water or EDTA, which suggests a reversible binding of Pb 2+ to yeast cell walls. Pb 2+ probably inhibited flocculation by competing with Ca 2+ , since Pb 2+ inhibition was alleviated by excess of Ca 2+ . Using a fluorescent avidinfluorescein isothiocyanate (Avidin‐FITC) probe, active cell surface flocculation lectins, in the presence of Ca 2+ ions, were visualized. Conversely, Avidin‐FITC was not fixed to yeast walls of flocculent cells, in the presence of Pb 2+ ions or in the simultaneous presence of 0.05 mM Ca 2+ and 0.4 mM Pb 2+ . These results suggest that Pb 2+ ions were not able to induce the correct conformation of the lectin‐like component and reinforces the hypothesis that Pb 2+ ions compete for the same “calcium site” of flocculation zymolectins.