Ethanol Levels Produced by Saccharomyces cerevisiae In the Presence of Oxygen with Increased Sugar Levels

Bailey Robertson, Ainsley Roark, Mailee Rohus, Bailey Rubin, Graham Davis


This experiment was conducted to determine how increased sugar levels available to Saccharomyces cerevisiae (yeast) in the presences of oxygen (O2) affect ethanol production. Interest in this particular topic arose due to the significance role yeast plays in the production of commercial products such as alcoholic beverages and biofuel as well as its influence on ecosystems, animals, and the human body. Our lab group was curious how increased sugar concentration affects yeast viability, specifically concerning ethanol production in the presence of confirmed O2 levels. Our hypothesis for this experiment is an increase in sugar concentration in the presences of Saccharomyces cerevisiae will increase ethanol production and O2 rates will initially remain constant. To conduct this experiment, we made two large batches of solution (control and experimental solutions). The experimental solution had a 100% increase of sugar (doubled) compared to the controlled experiment and was 1.5% weight-by-volume of sugar concentration compared to the controlled experiment, 0.75% weight-by-volume. Ethanol and O2 probes were inserted into each chamber to track the concentrations through the trials. Our data showed O2 concentrations for the O2 control group, which had an increased average of 17.56% compared to the O2 experimental group which has an average change of 45.32%. This verified O2 was present throughout the trials. In the control groups, ethanol percentages increased between the initial and final test points in each trial. The ethanol production data recorded in the experimental groups showed elevated ethanol production when compared to the control group. Ethanol concentrations increased between the initial and final test points for each experimental trial. The average difference between the initial and final data points in the control group ethanol production was 300% compared to the experimental group average percent difference of 350%. Overall, this experiment helped us to understand how increasing sugar available to Saccharomyces cerevisiae affects aerobic ethanol production, which can be used to benefit commercial production efforts, the ecosystem, animal health, and the human body.

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