The influence of temperature on the growth inhibitory effect of carbon dioxide on Pseudomonas fragi and Bacillus cereus.

The growth inhibitory effect of 50 kPa (0.5 atm) CO2 was tested for Pseudomonas fragi in the temperature range 5-35 degrees C and of 101 kPa (1 atm) CO2 on Bacillus cereus in the range 18-46 degrees C. The maximum specific growth rate (mumax) of P. fragi in air (pH 6.7) was 0.44 h-1 at 35C, 0.66 h-1 at 30 degrees C, and 0.078 h-1 at 5 degrees C. In 50 kPa of CO2 in air the relative inhibition of the growth rate was about 30% at 35 degrees C, 50% at 30 degrees C, and 90% at 5 degrees C. Thus, the inhibitory effect of CO2 successively increased with decreasing temperature, an effect which was explained by the increasing solubility of CO2 with decreasing temperature. The anaerobic growth of B. cereus (101 kPa N2) was optimal at 40 degrees C and stopped at temperatures below 18 degrees C and above 46 degrees C. The relative inhibitory effect of 101 kPa CO2 at the optimum growth temperature was about 40%; this increased to 100% near the maximum and minimum growth temperatures. The growth inhibitory effect of reduced temperature (below optimum) and CO2 and B. cereus was larger than that expected from the increased solubility of CO2 at lower temperatures.