Pathways of D-fructose catabolism in species of Pseudomonas

Cell-free extracts of D-fructose grown cells of Pseudomonas putida, P. fluorescens, P. aeruginosa, P. stutzeri, P. mendocina, P. acidovorans and P. maltophila catalyzed a P-enolpyruvate-dependent phosphorylation of D-fructose and contained 1-P-fructokinase activity suggesting that in these species fructose-1-P and fructose-1,6-P2 were intermediates of D-fructose catabolism. Neither the 1-P-fructokinase nor the activity catalyzing a P-enolpyruvate-dependent phosphorylation of D-fructose was present in significant amounts in succinate-grown cells indicating that both activities were inducible. Cell-free extracts also contained activities of fructose-1,6-P2 aldolase, fructose-1,6-P2 phosphatase, and P-hexose isomerase which could convert fructose-1,6-P2 to intermediates of either the Embden-Meyerhof pathway or Entner-Doudoroff pathway. Radiolabeling experiments with 1-14C-D-fructose suggested that in P. putida, P. aeruginosa, P. stutzeri, and P. acidovorans most of the alanine was made via the Entner-Doudoroff pathway with a minor portion being made via the Embden-Meyerhof pathway. An edd- mutant of O. putida which lacked a functional Entner-Doudoroff pathway but was able to grow on D-fructose appeared to make alanine solely via the Embden-Meyerhof pathway.