Stir it Up: A Study of the Effect of Agitation on CO2 Output in Saccharomyces cerevisiae Yeast

Reagan Conrad, Jorja Ford, Brylee Maddox, Krystal Rodriguez, Emilee Harmon


One of the ways yeast’s, particularly Saccharomyces cerevisiae, carbon dioxide output is affected is through its relationship with the amount of agitation it endures through methods like stirring. The levels of stirring, (level 3, 2, 1, and 0), are key components in increasing CO2 output, which varies directly with the growth of yeast. This led us to conduct this experiment in order to determine which level of agitation causes the CO2 output in yeast to be the greatest. We hypothesized that the yeast will produce the most CO2 when stirred on level 3 (250 rpm), since it is going through the highest level of agitation. To find the answer to our hypothesis, we used a mixture of 39 mL of water, 80 μL of sodium phosphate twice, 0.80g of sugar, and 1 mL of yeast solution. Putting the mixture through different levels of stirring on the stir station like levels 3 (250 rpm), 2 (150 rpm), and 1 (50 rpm) to determine the greatest rate of CO2 output, along with level 0 as the control group. We found that level 3 had the greatest CO2 output, while level 2 had the lowest CO2 output. This means that our hypothesis is somewhat valid and aligns with the final results. It follows our hypothesis that the higher the level/rpm the more CO2 will be produced; however, level two does not follow this trend.

Full Text:



Brase, S., Riley, A., Canady, J., and L. Black. 2017. Yeast is a Beast at Producing CO2. Journal of Introductory Biology Investigations. 7:3.

Collinson, P., Young, I., Antal, L., and H. Macbeth. 2019. In Praise of a Fermented Bread: An Ethiopian Recipe for Frugal Sustainability. Food and Sustainability in the Twenty-First Century: Cross-Disciplinary Perspectives. 157-171.

French, D.P. 2021. Investigating Biology: A Laboratory Resource Manual. Ed. Moria Harmon. 2021 Edition. Fountainhead Press, USA. AB&B.1 - AB&B.12.

Magdoff, Fred. 2008. The World Food Crisis: Sources and Solutions. Monthly Review. 60:1.

Rice, J.F., Helbert R., and J.C. Carver. 1974. The Quantitative Influence of Agitation on Yeast Growth during Fermentation. Journal of American Society of Brewing Chemists. 32:2, 94-96.

Vernier. 2009. Stir Station (Order Code STIR). Vernier Software and Technology. 1-4.


  • There are currently no refbacks.