Gaseous environments modify reserve carbohydrate contents and cell survival in the brewing yeast Saccharomyces cerevisiae

Abstract

The use of H(2), He and O(2) during batch fermentation of Saccharomyces cerevisiae BRAS291 increased the final intracellular glycogen contents of the cells from 2-fold to 10-fold compared with a gas-free condition, and this depended on the gas applied. Differently, the intracellular trehalose contents increased from 2-fold to 10-fold in reducing conditions compared with more oxidizing conditions. During storage at 4 degrees C, the viability of cells cultivated with gas was twice that of cells cultivated without gas. These results could be explained by the intracellular carbohydrate contents as well as yeast ultrastructural modifications observed previously.

The Microbiology of Malting and Brewing

“…Glycogen has attracted much study as an important carbon and energy reserve in brewing yeast (62), while the importance of trehalose as a stress protectant is well studied (63).…”

Gaseous environments modify physiology in the brewing yeastSaccharomyces cerevisiaeduring batch alcoholic fermentation

“…Viable yeast cell concentration was monitored using a methylene blue staining method as described previously (Pham et al. 2008).…”

“…Assuming cells of S. cerevisiae BRAS291 to be spherical, the volume ( V ) was then calculated from the measured area. Measurement was performed on 100 cells at a minimum (Pham et al. 2008).…”

“…The fully defined medium constituted by Kennedy et al (1997) and Taidi et al (2003) was used as previously described (Pham et al 2008). The cultures were carried out at 28°C during 13 days with permanent stirring (250 rev min )1 ) in a Biostat Q batch fermentation system.…”

“…Viable yeast cell concentration was monitored using a methylene blue staining method as described previously (Pham et al 2008). Methylene blue solution consisted of: 0AE025% methylene blue (Sigma-Aldrich, USA), 0AE9% NaCl, 0AE042% KCl, 0AE032% CaCl 2 , 0AE02% NaHCO 3 and 1% glucose.…”