Factors which Affect the Size of the Organisms and the Optical Density of Suspensions of Pseudomonas aeruginosa and Escherichia coli

When water-washed organisms of a strain of Pseudomonas aeruginosa were exposed to solutions of NaCl or sucrose, they shrank in size and became more dense. The optical density of suspensions increased rapidly. Pre-treatment of the organisms with various cations, surface-active agents and heat and cold, affected the reaction, and the organisms then behaved differently toward NaCl and sucrose. Some but not all of the effects observed with P. aeruginosa were also observed with a strain of Escherichia coli.