Effect of varying temperature on the rate of CO2 production in baker’s yeast (<i>Saccharomyces cerevisiae</i>)


  • Hillary Janssens
  • Lisa Kim
  • Icel Lee
  • Melody Salehzadeh


We conducted an experiment to find the optimal temperature for cellular respiration of Saccharomyces cerevisiae. Respirometers were incubated in water baths at temperatures of 25°C, 30°C and 35°C. The amount of CO2 gas produced was recorded at five minute intervals for 70 minutes, and cell counts were made before and after incubation. The notable trend in our data was that with increasing temperature, there was less of a lag time before measurable CO2 appeared, and CO2 production was more rapid than at lower temperatures. The average CO2 production rates were 1.66  10-9 ± 6.95  10-10 mL/cell, 2.31  10-9 ± 6.76  10-10 mL/cell and 3.02  10-9 ± 6.42  10-10 mL/cell at 25°C, 30°C and 35°C, respectively. Based on previous research, the lower rate of CO2 production observed at 25°C is a result of reduced enzyme kinetics and reaction rates at lower temperatures. Additionally, the accelerated rate of CO2 production seen at 30°C, and even more so at 35°C, can be explained by the increase in enzyme kinetics, membrane fluidity and diffusion rates that accompany higher temperatures. Our results suggest that the optimal temperatures for S. cerevisiae growth and metabolism may not be equal.