The effect of changes in temperature on the doubling time of wild-type Tetrahymena thermophila

Abstract

Tetrahymena thermophila is a single celled protozoan commonly found in freshwater habitats (Cassidy-Hanley 2012). In this study, we investigated the relationship between changes in temperature and doubling time in Tetrahymenathermophila. In our experiment, T.thermophila was incubated at three different temperatures: 30°C, 35°C, and 40°C. Our data were collected at three hour intervals from 0h to 9h, with a final sample taken at 10h. The population size was determined by placing 20 μL of fixed T. thermophila cells onto a haemoctyometer and counting the cells using the Axio Star microscope. The doubling time was lowest at 35°C (4.22 h) compared to the doubling time at 30°C (7.37 h) and 40°C (5.63 h). Based on calculations of the one-way ANOVA, we failed to reject our null hypothesis (p = 0.49); therefore the doubling time of Tetrahymena thermophila was longer or the same at 35°C. Although we failed to reject our null hypothesis, trends were still consistent with previously conducted experiments, stating that growth rates were highest at optimal temperature (Frankel and Nelsen 2001).