A Sweet Tooth for Dextrose: The Differing Effects of Monosaccharide and Disaccharide Sugars on Fermentation in Saccharomyces cerevisiae

Madi Moore, Rachel Hamrock, Caitin Parker, Rabeca Richardson, McKenzie Menefee


Saccharomyces cerevisiae, baker’s yeast, has become a major contributor to various areas of manufacturing–like baking, brewing, and biofuel production. Fermentation of yeast produces products essential for each of these processes. However, fermentation is extremely sensitive to various factors–with the type of sugar present being one of them. We explored how the presence of a monosaccharide sugar, dextrose, and disaccharide sugars, sucrose and lactose, affected the rate of fermentation in baker’s yeast. We hypothesized that the more complex sugars, sucrose and lactose, would have a lower rate of fermentation and, thus, a lower carbon dioxide output than the simple sugar dextrose. We recorded the carbon dioxide production of the yeast for the three different sugars over fifteen-minute periods in order to calculate the rate of fermentation. The results concluded that the yeast produced carbon dioxide at a drastically slower rate in the presence of sucrose and lactose than it did in the presence of dextrose. Therefore, sucrose and lactose induced a slower rate of fermentation than dextrose–with lactose having the slowest. We can then conclude that Saccharomyces cerevisiae can break down monosaccharide sugars faster than it can break down disaccharide sugars, which may be important information to know in order to develop the ideal sugar ratio for commercial yeast usage.

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