Analyzing the Effects of Fertilizer Concentration on the Rate of Food Vacuole Formation in Tetrahymena thermophila

  • Annie Faragher
  • Joo Hwan Seo
  • Estrella Vilchis
  • CK Wong


The unicellular ciliate Tetrahymena thermophila plays an important role in freshwater aquatic ecosystems, and through the use of phagocytosis, may be impacted by agricultural runoff. The purpose of this study was to determine the effects of varying concentrations of fertilizer on the rate of food vacuole formation. Plant-Prod, a water soluble fertilizer, was diluted using T. thermophila nutrient media and combined with 2 mL of T.thermophila culture to create three replicates of three different treatments with a total volume of 4 ml. Treatment A was 20% of the base fertilizer solution, 0.8ml/L, Treatment B 5%, 0.2ml/L, and Treatment C was the control, containing no fertilizer. After 24 hours of incubation at 20 ° C, black dye was added to each test tube to allow for the identification of newly formed food vacuoles. 100 uL of sample was removed at 10 minutes, 150 minutes, and 210 minutes from each replicate, and placed with fixative in eppendorf tubes. The number of stained vacuoles in 5 T.thermophila cells were then counted using a compound microscope. We conducted a one-way ANOVA [F (2, 132) = 4.12, p = 0.05], and found that the presence of increased concentrations of fertilizer significantly increased the rate of food vacuole formation in treatment A (0.12 ± 0.02) and treatment B (0.08 ±0.01) compared to treatment C (0.063 ± 0.01). The rate of food vacuole formation was positivelycorrelated with fertilizer concentration. The data did support the prediction that increasing the concentration of fertilizer would increase the rate of food vacuole formation.