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

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Abstract
The inhibiting action of NaN3 on catalase derived from animal tissue has been well demonstrated, but there is little information about its action on bacterial catalase. Washed suspensions of bacteria in PO4 buffer (pH 7.4) were used to minimize the effect of peroxidase. These suspensions, with and without the addition of NaN3, were allowed to react with H2O2, acidulated with H2SO4, and titrated with standard KMnO4. Results were expressed as ml. of 0.1 N H2O2 decomposed. 11 spp. of bacteria which produced catalase were used in the study. Conc. of NaN3 of 0.01 and 0.02% (M/650 and M/325) markedly inhibited the catalase activity of suspensions of washed bacteria. The reversibility of this inhibition was established, although with increased time exposure to the chemical the amt. of reversibility diminished. The inhibition of catalase by NaN3 in actively proliferating cells was also determined and found to agree closely with the results obtained with resting cells, with the exception of P. aeruginosa. Introduction of catalase into media previous to its inoc. with bacteria did not affect the sensitivity of the bacteria tested to NaN3. Attempts to demonstrate the presence of H2O3 in cultures of bacteria in the presence of NaN3 were unsuccessful. The marked correlation between NaN3 sensitivity and inhibition of catalase activity is pointed out and may be due to the inability of selectively inhibiting catalase by NaN3 in the presence of other heme-containing respiratory enzymes.

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