Beauty and the Yeast: The Effects of Monosaccharides, Disaccharides, and Polysaccharides on the Carbon Dioxide Production of Saccharomyces cerevisiae

Jonathan Kelvington, Cameron Major, Caleb Mollet, Baileigh Vial



Baker’s yeast, also known as Saccharomyces cerevisiae, is a unicellular microorganism that is critical in a number of industrial processes, such as brewing, baking, and the production of biofuels (French 2021). When yeast is exposed to a high concentration of sugar, its respiration is inhibited and it undergoes aerobic fermentation, in which carbon dioxide and ethanol are produced. There are a variety of factors that contribute to the fermentation of yeast, one of which being the type of sugar used for fermentation. In this experiment, we studied the effect that different types of carbohydrates have on the fermentation rate of Saccharomyces cerevisiae. We used dextrose, sucrose, and starch as the three different types of carbohydrates. By creating mixtures of 0.8 g of each sugar, water, sodium phosphate, and yeast, we were able to compare the carbon dioxide output of yeast when exposed to a monosaccharide (dextrose), disaccharide (sucrose), and polysaccharide (starch). It was hypothesized that the monosaccharide, dextrose, would yield the highest carbon dioxide output and therefore fermentation rate because it is the least complex carbohydrate. This would allow the yeast to use up less energy to break it down when compared to the disaccharide and polysaccharide. After analyzing data, it was concluded that our hypothesis was supported. Dextrose, the monosaccharide, saw the highest fermentation rate, followed by sucrose and starch, respectively. It is important that future studies are conducted to find maximal conditions for yeast fermentation.

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