Oxidative pathways in a fluorescent Pseudomonas

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Abstract
A strain of the Pseudomonas fluor-escens group (KB 1), isolated from soil,oxidized succinate incompletely, with the uptake of approx. 1.5 moles O2 /mole succinate and accumulation of alpha-ketoglutarate and pyruvate. The yield of alpha-ketoglutarate formed from succinate was variable, but could account for up to 70% of the O2 consumed. alpha-Ketoglu-tarlc acid as the 2,4-dinitrophenylhydrazone was isolated from a growth medium containing succinate as sole source of C. Washed suspensions of cells grown with succinate as the sole source of C oxidized citrate, isocitrate, cis-aconitate and alpha-ketoglutarate after a lag period. These adaptations were inhibited by irradiating the suspensions with u.-v. light. Washed suspensions of cells grown with citrate as the sole source of C-oxidized succinate and alpha-ketoglutarate only after a lag period and irradiation of the suspension with u.-v. light inhibited these adaptations. Cell-free extracts of cells grown on a medium containing either succinate or citrate contained the following enzymes: succinic dehydrogenase, fumarase, malic dehydrogenase, oxaloacetic de-carboxylase, aconitase, isocltrlc dehydrogenase and alpha-keto-glutarlc oxidase. The role of the tricarboxylic acid cycle in the oxidation of succinate and the technique of simultaneous adaptation for the study of the tricarboxylic acid cycle in micro-organisms are discussed.