Abstract
Yeast flocculation is the reversible aggregation of yeast cells promoted
by the interaction between lectin-like protein receptors with mannose
side chains on adjacent cell walls. Flocculation is governed by several
physiological factors, including the type of nutrient sugar available to
yeast. We grew four industrial strains of Saccharomyces cerevisiae,
representing applications in the brewing, winemaking and bioethanol
sectors, to late stationary phase and quantified the cellular content of
mannans, glucans and lectin-like proteins on yeast cell surfaces.
Results indicated that brewing and champagne strains showed moderate to
high flocculation ability when grown with glucose, fructose, maltose or
galactose, whereas winemaking and fuel alcohol strains only showed
moderate flocculation when grown on maltose and galactose. All yeast
strains studied were weakly flocculent when grown on mannose. With
regard to lectin-like receptors, their number played a more important
role in governing yeast flocculation than the mannan and glucan contents
in yeast cell walls. We conclude that all the industrial strains of S. cerevisiae
belonged to New-Flo type on the basis of their flocculation behaviour
observed when cultured on different sugars. Quantification of yeast cell
wall polysaccharides and receptor sites indicates that mannan and
glucan levels remain almost constant, irrespective of the strain under
investigation. The main difference in flocculation characteristics in
industrial yeast strains appears to be due to variations in
concentrations of lectin-like cell surface receptors. Our findings may
benefit brewers, winemakers and other yeast-based technologies in design
of media to prevent premature flocculation during fermentation.
Original language | English |
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Pages (from-to) | 211–218 |
Number of pages | 8 |
Journal | Journal of the Institute of Brewing |
Volume | 123 |
Issue number | 2 |
Early online date | 29 Mar 2017 |
DOIs | |
Publication status | Published - 8 May 2017 |
Keywords
- Carbon source
- Flocculation
- New-flo phenotype
- Lectin staining
- Saccharomyces cerevisiae
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Student Theses
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Yeast flocculation: understanding cell surface structure-function relationships in industrial yeast strains
Author: Nayyar, A., Jun 2015Supervisor: Walker, G. M. (Supervisor) & Deeni, Y. (Supervisor)
Student thesis: Doctoral Thesis
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