Effect of increasing glucose concentrations on the growth rate of Tetrahymena thermophila

Gilbert Lee, Alexia Magarian, Vivian Ng, Sajjal Pirzada


The protozoan, Tetrahymena thermophila, is an effective model organism due to its short generation time of approximately two hours. It has displayed even faster growth rates in the presence of nutrients, such as glucose, by phagocytizing and storing them in food vacuoles. The aim of our study was to expose T. thermophila to various glucose concentrations, treatments of 0.2%, 2%, 4%, and 6% so we could produce an effective synthetic medium that would supply abundant Tetrahymena cells for experimentation. We hypothesized that growth rate would be greatest at 4% glucose with a decrease at 6% glucose due to differential oxygen pressures resulting from the saturation of glucose within the media. In our study, we placed the T. thermophila in an SPP medium varying the glucose concentration with each treatment. We then determined cell density after initial cultivation at 1, 3, 5, and 7 hours using a haemocytometer. Greatest growth rate was found at 2% glucose with 21,844 cells/mL and lowest in the 6% glucose with 8,220 cells/mL. Using a one-way ANOVA test, we found our p-value to be statistically significant; however, because the growth rate was highest for 2% rather than the predicted 4%, we could not reject our null hypothesis.

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