Fermentation of Yeast: How Complexity and Chemical Makeup of Nutrients affect Fermentation

Bridget Ha, Houston Gill, Jarrod Greiner, Heath Ferguson, Kelsey Brass


Baker’s yeast (Saccharomyces cerevisiae) is a microorganism that is capable of consuming glucose and using it to produce oxygen, carbon dioxide, and ethanol through a process known as fermentation. Curious about the effect of different compounds with varying complexities and chemical makeup on the fermentation process, we designed an experiment that would be able to analyze how the yeast would respond when it was introduced to three different compounds: Glucose, sucrose, and iodized salt. For our experiment, we predicted that when iodized salt served as the primary nutrient for yeast, fermentation would be inhibited, lowering the rate of carbon dioxide production. Furthermore, we predicted that when the yeast was exposed to sugars of different complexities, the carbon dioxide production rate would be higher for the solution containing the more complex compound, which for this experiment was sucrose. To test our hypothesis, we conducted a total of nine trials (Three trials for each compound), each of which were 15 minutes long so that at least five minutes of the log phase could be accounted for. Each of the different compounds was added to a standard yeast solution and a Vernier CO2 gas probe was used to record the amount of carbon dioxide produced by the system. The average rate of carbon dioxide gas production was then calculated for each of the compounds. From the data collected, we concluded that our hypothesis that the salt solution would result in the lowest rate of carbon dioxide production. However, our data did not support our prediction that the more complex polysaccharide would produce a higher rate of carbon dioxide output.

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