THE EFFECT OF CERTAIN DRUGS ON NITROGEN ASSIMILATION IN PSEUDOMONAS AERUGINOSA

¹ Department of Physiology and Pharmacology, Duke University School of Medicine, Durham, North Carolina

1. Washed suspensions of a strain of Pseudomonas aeruginosa assimilate ammonia when members of the tricarboxylic acid cycle and related compounds are oxidized. The oxidation rate of these compounds is increased during the assimilation, but the amount of oxygen consumed is unaltered.

2. Ammonia is produced from urea and purines only when one of the substrates is being oxidized and is subsequently assimilated in part.

3. Streptomycin at pH 6.0 does not inhibit the oxidation of the substrates but prevents the increased oxidation rate and thus both the assimilation of ammonia and its production from urea and purines.

4. Benzoate, salicylate, p- and m-hydroxybenzoate, p-aminobenzoate and related compounds inhibit to some extent the oxidation of the substrates but they have a greater effect on the production of ammonia and on the increased oxidation rate accompanying its assimilation. They affect the oxidation of succinate more than that of other substrates and are more active at pH 6.0 than at pH 7.8. Sulfa drugs are without effect on oxidation or assimilation.

5. Certain diamidines behave like the benzoates but are more active at pH 7.8 than at pH 6.0.

6. 5-Aminoacridine and fluoroacetate inhibit the oxidation of all substrates tested and inhibit the increased oxidation rate to an equal extent. The former is more active at pH 7.8, the latter is equally active at pH 7.8 and pH 6.0.