Tricarboxylic acid cycle in Pseudomonas aeruginosa.

During the past few years scattered information has appeared which indicates that at least some bacteria probably possess a tricarboxylic acid cycle. Lockwood and Stodola found that Pseudomonas jluorescens formed considerable quantities of a-ketoglutaric acid when growing on a glucose medium under conditions of intense aeration (1). Ajl and Werkman found evidence for at least parts of the conventional cycle in Escherichia co2i (2). However, Karlsson and Barker (3) were not able to demonstrate the presence of this system in Azotobacter agile, either by the technique of simultaneous adaptation or by radioactive tracers. In contradiction to this latter work Stern and Ochoa (4) were able to show that both A. agile and E. wli possess the enzyme necessary for the condensation of oxalacetate and “active acetate” to citrate. Since Karlsson and Barker did not report on the activity of the organism towards the Ce members of the tricarboxylic acid cycle, it is not possible to decide whether the technique of simultaneous adaptation is applicable to the detection of the intermediates of the tricarboxylic acid cycle or whether A. agile possesses only fragments of the cycle. The present study was undertaken in an effort to detect a tricarboxylic acid cycle in Pseudomonas aeruginosa and thereby to elucidate further the pathway of glucose oxidation in this organism.