The effect of temperature on the growth rate of Chlamydomonas reinhardtii.

Abstract

Chlamydomonas reinhardtii is a unicellular green alga commonly found in freshwater ecosystems. Despite this organism’s wide use in research within cell biology, the optimal growth temperature is not well defined. Given the optimal temperature range of this organism provided by the literature, we hypothesized that 25°C would be the optimal temperature, resulting in the greatest growth rate (cells mL^-1 day^-1), and that temperatures below and above this value (17 and 30 °C) would decrease the growth rate of this organism. We conducted an 11-day study with a total of five sampling days. C. reinhardtii was cultivated at three incubation temperatures of 17˚C, 25˚C and 30˚C. The number of cells was counted using a compound microscope and a haemocytometer. A one-way ANOVA test was performed, resulting in a significant p-value of 0.0033. Following, we conducted a Tukey-Kramer HSD test and found that there was a significant difference in growth rate (cells mL^-1 day^-1) between treatments at 25 and 30°C and between treatments at 25 and 17°C, with p-values of 0.0031, 0.0155, respectively, lending support to our alternate hypothesis.