Growth Inhibition of a Pseudomonas by Carbon Dioxide

Abstract

SUMMARY— Growth rate studies were conducted with Pseudomonas aeruginosa to measure the inhibitory effect of CO 2 when such variables as temperature, O 2 , tension, pH, and ionic strength of the glucose‐salts medium were controlled. Depletion of O 2 did not limit growth until more than 75% (v/v) of the air was replaced with nitrogen. Generation time increased with ionic strength of the medium. The influence of pH in the range of 6.0 to 7.4 on the growth rate was negligible. When these variables were controlled, a linear relationship between generation time and CO 2 composition of the gas phase was observed. At 70% CO 2 (v/v), the generation time was nearly doubled. Thus, CO 2 inhibits the metabolism of the organism, and this inhibition is due to gaseous CO 2 in the air only when other environmental factors are controlled.