https://doi.org/10.17113/ftb.53.01.15.3617
Effect of Ethanol Stress on Fermentation Performance of Saccharomyces cerevisiae Cells
Immobilized on Nypa fruticans Leaf Sheath Pieces
Hoang Phong Nguyen, Hoang Du Le and Van Viet Man Le*
Department of Food Technology, Ho Chi Minh City University of Technology, 268 Ly Thuong Kiet Street, District 10,
70000 Ho Chi Minh City, Vietnam
Article history:
Received February 16, 2014
Accepted November 7, 2014
Key words:
Saccharomyces cerevisiae, immobilized yeast, ethanol stress, Nypa fruticans, fatty acids
Summary:
The yeast cells of Saccharomyces cerevisiae immobilized on Nypa fruticans leaf sheath pieces were tested for ethanol tolerance (0, 23.7, 47.4, 71.0 and 94.7 g/L). Increase in the initial ethanol concentration from 23.7 to 94.7 g/L decreased the average growth rate and concentration of ethanol produced by the immobilized yeast by 5.2 and 4.1 times, respectively. However, in the medium with initial ethanol concentration of 94.7 g/L, the average growth rate, glucose uptake rate and ethanol formation rate of the immobilized yeast were 3.7, 2.5 and 3.5 times, respectively, higher than those of the free yeast. The ethanol stress inhibited ethanol formation by Saccharomyces cerevisiae cells and the yeast responded to the stress by changing the fatty acid composition of cellular membrane. The adsorption of yeast cells on Nypa fruticans leaf sheath pieces of the growth medium increased the saturated fatty acid (C16:0 and C18:0) mass fraction in the cellular membrane and that improved alcoholic fermentation performance of the immobilized yeast.
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