A Preliminary Study: Effect of low pH environments on the food vacuole formation rate of Tetrahymena thermophila

Abstract

Tetrahymena thermophila are ciliates found in freshwater aquatic systems that fulfill their nutritional needs through the process of phagocytosis by food vacuole formation. This experiment aims to study the effects of decreasing pH on the metabolism of this microorganism over time by observing its food vacuole count and formation rate. T. thermophila were exposed to three treatment conditions of pH 5, pH 6, and pH 7 over a two-hour period. Samples were taken from each treatment every 10 minutes, and the average number of food vacuoles formed between 10 Tetrahymena cells was observed and recorded from every 10-minute time interval. Our research suggests that T. thermophila formed more food vacuoles and at a higher rate at pH 7, while pH 5 displayed dramatically less vacuole formation. Rate of food vacuole formation per minute was calculated following exposure to pH 5, pH 6, and pH 7 after two hours and was found to be 0.011, 0.036, and 0.046 vacuoles per minute respectively. Considering that the natural habitats of Tetrahymena are usually at pH levels of approximately 7, we can infer that this is the state in which this microorganism is most comfortable. This is likely why T. thermophila do not perform well at decreased pH levels, resulting in an inability to form as many food vacuoles.