Cell-free extracts of Pasteurella pseudotuberculosis and P. pestis catalyzed a rapid and reversible exchange of electrons between pyridine nucleotides. Although the extent of this exchange approximated that promoted by the soluble nicotinamide adenine dinucleotide (phosphate) transhydrogenase of Pseudomonas fluorescens, the reaction in the pasteurellae was associated with a particulate fraction and was not influenced by adenosine-2'-monophosphate. The ability of P. pseudotuberculosis to utilize

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... this system for the maintenance of a large pool of nicotinamide adenine dinucleotide phosphate could not be correlated with significant participation of the Entner-Doudoroff path or catabolic use of the hexose-monophosphate path during metabolism of glucose. As judged by the distribution of radioactivity in metabolic pyruvate, glucose and gluconate were fermented via the Embden-Meyerhof and Entner-Doudoroff paths, respectively. With the exception of hexosediphosphatase, all enzymes of the three paths were detected, although little or no gluconokinase or phosphogluconate dehydrase was present unless the organisms were cultivated with gluconate. The significance of these findings is discussed with respect to the regulation of carbohydrate metabolism in the pasteurellae, related enteric bacteria, and P. fluorescens. 0.025 M K2HPO4, 0.01 M citric acid, 0.0025 M MgC92, and 0.0001 M FeC12, was used in all culture media. Flasks (1-liter) containing 100 ml of this base plus 4 g of Casitone (Difco) were autoclaved and neutralized with NaOH. Then the medium received 1 ml of stock solutions of 0.25 M CaCl2, 0.25 M Na2S2O3, and 1.0 M carbohydrate (sterilized by filtration). After inoculation with 107 cells per rnl, the cultures 1698 on May 9, 2020 by guest