The Effects of Copper Concentration on the Growth Rate of Tetrahymena thermophila
Abstract
The growth of Tetrahymena thermophila can be affected by the concentration of heavy metals, like copper, in their environment. The focus of this study was to examine how T. thermophila responds to increasing concentrations of copper in the growing media. Treatments of T. Thermophila suspended in SSP medium and copper concentrations of 0 ppm, 1 ppm, 3 ppm, and 5 ppm were incubated at 35oC while maintaining all other factors constant. Cell counts for T0 were done before incubating. Cell counts for T1 to T4 were done after incubation in increments of 2.5 hours. T5 was performed 24 hours after initial incubation and the last observation at T6 was done at 26.5 hours after incubation. It was observed that the growth rate was slow from T1 to T3 and then the growth rate increased until the end of the experiment. The highest average growth rate was found to be in the concentration of 1 ppm with a growth rate of 7293 cells/hour and the lowest average growth rate was found in the treatment at 5 ppm with a growth rate of 6528 cells/hour. After analysis by a one-way ANOVA, the null hypothesis for the effects of copper concentration and growth rate was rejected. Further statistical post-hoc analysis using a Tukey test found there was a significant difference between mean growth rates in the 3 ppm and 5 ppm copper treatments. Further experiments must be performed over a longer period of time, more treatment groups, and more concentrations between 3 ppm and 5 ppm in order to determine the exact copper tolerance level for T. thermophila.
