Studies of the Effect of Sodium Azide on Microbic Growth and Respiration

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Abstract
To ascertain the influence of NaN3 on microbic growth, 92 strains of bacteria were selected. In conc. of 0.01-0.03% in infusion agar the chemical was bacteriostatic for gram-negative bacteria. Of the 41 strains tested, only 3 strains of Pseudomonas aeruginosa grew in the presence of 0.03%. Streptococci, pneumococci, anaerobes and lacto-bacilli were resistant to 0.03% NaN3. The gram-positive spore-forming aerobes, and Staphylococcus citreus were moderately resistant. Results using NaN3 broth were similar to those with solid media, with the exception that P. aeruginosa was very sensitive in this medium. The marked resistance of certain streptococci was shown, since 3 of 8 strains grew well in glucose broth containing 0.25% NaN3 Staph. albus, Staph. aureus, and P. aeruginosa were more susceptible to NaN3 under anaerobic conditions than in the presence of free O2. The resistance of P. aeruginosa was studied further, and it was ascertained that aeration of NaN3 broth cultures of a pyocyanine-producing strain of P. aeruginosa increased the growth of the organism in the presence of the chemical. Using washed inocula, the growth of P. aeruginosa in the presence of NaN3 under aerobic conditions was reduced.