Exploring the effects of temperature on the growth rate of Tetrahymena thermophila


  • Heather Cathcart
  • Diana Dadkhah
  • Mingzeng Qin
  • Raman Sandhu


The objective of the study was to determine the effect of temperature on T. thermophila growth
rate. T. thermophila are free-living unicellular eukaryotes that are found in freshwater lakes, ponds, and
streams. We measured the growth rate of T. thermophila at temperatures of 20°C, 35℃ and 41℃. There
were three replicates per temperature treatment. Cell counts were taken at 0, 3, 21, 24, 27, and 45 hours
and were used to determine the growth rate. Our results showed that the 20°C treatment had the highest
growth rate, followed by the 35°C treatment, and the 41°C had the lowest growth rate. One-way ANOVA
and Tukey's multiple comparison test were performed to determine the significance of the results. The
one-way ANOVA was run on samples, including hour 3, which showed no statistical significance
between the groups (p = 0.0575). Hour 3 was then excluded from the data due to human error during cell
counting, and another one-way ANOVA was run, which was found to be statistically significant (p =
0.0157). Based on Tukey’s multiple comparisons test, there was statistical significance found between
20°C treatment and 35°C treatment (p= 0.0407) and 20°C treatment and 41°C treatment (p=0.0169).
There was no statistical significance found between 35°C treatment and 41°C treatment (p=0.7429).
Given these results, we can reject the null hypothesis that temperature will not affect the growth rate of T.
thermophilia at various temperatures and accept the alternative hypothesis for the dataset excluding hour
3. Thus, we can conclude that temperature has an effect on T. thermophilia growth rate.