Effect of different starvation conditions on the flocculation of Saccharomyces cerevisiae

摘要

Aims: To study the effect of different starvation conditions on the flocculation of an ale brewing yeast of Saccharomyces cerevisiae NCYC 1195. Methods and Results: Flocculation was assessed by a micro-flocculation technique (Soares and Mota 1997). Carbo-starved cells of a NewFlo phenotype strain did not lose flocculation during a 48 h period. Cells incubated only in the presence of fermentable carbon sources (glucose, galactose and maltose at 2%, w/v), shoed a progressive flocculation loss. The incubation of cells in 4% (v/v) glucose and 15 μg ml~(-1) cycloheximide hindered flocculation loss. The presence of 0.1 mmol l~(-1) PMSF or 10 mmol l~(-1) EDTA prevented partially or completely, respectively, the loss of flocculation in the presence of glucose. Conclusions: Fermentable sugars induced a flocculation loss, which seems to require de novo protein synthesis and the involvement of different proteases. Significance and Impact of the Study: The findings reported here contribute to the elucidation of the role of nutrients on the physiological control of yeast flocculation.