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The endogenous respiration of Pseudomonas aeruginosa Warren, R.A.J.


A study of the endogenous respiration of the aerobic bacterium Pseudomonas aeruginosa was undertaken with a view to establishing the nature of the endogenous substrate and the relationship, if any, of the endogenous respiration to the oxidation of exogenous substrate. It was shown that the only end-products accumulating during endogenous respiration were ammonia and carbon dioxide. There were no detectable changes in the carbohydrate, lipid, nucleic acid or protein content of the cells during endogenous respiration. Inhibitor studies showed that protein was an endogenous substrate, and this was confirmed by the fact that after endogenous respiration succinate-grown cells required a slight induction period for succinate oxidation. Since keto-acids did not accumulate during endogenous respiration, the amino acids produced by protein degradation were probably oxidized to completion. Calculations based on this assumption showed that the ammonia production could account for all of the oxygen consumed. In the presence of an oxidizable substrate there was no production of ammonia. Manometric data showed that the endogenous respiration was not suppressed during the oxidation of an exogenous substrate. Inhibitor studies showed that oxidative assimilation involved the reassimilation of the ammonia produced by the endogenous respiration.

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