Mannitol and Fructose Catabolic Pathways of Pseudomonas aeruginosa Carbohydrate-Negative Mutants and Pleiotropic Effects of Certain Enzyme Deficiencies

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Abstract
Mutant strains of P. aeruginosa PAO were isolated on the basis of their inability to utilize mannitol as sole C source for growth. Four linkage groups (I through IV) among these mutant strains were resolved by 2-factor crosses using the general transducing phage F116, and the strains appeared to contain point mutations as evidenced by ability to give rise to spontaneous revertants with wild phenotype on mannitol minimal agar. Group I strains were affected only in ability to grow on mannitol; all were deficient in inducible mannitol dehydrogenase [EC 1.1.1.67] activity, and all but 1 were deficient in inducible mannitol transport activity. Fructokinase [EC 2.7.1.4] was induced in group I strains and in wild-type bacteria during growth in the presence of mannitol but not fructose, indicating the presence of a pathway specific for endogenously generated fructose. Cells grown on fructose contained phosphoenolpyruvate:fructose-1-phosphotransferase activity, and mannitol-grown cells contained a lower level of this activity. Group II mutants were deficient in constitutive phosphoglucoisomerase [EC 5.3.1.9], failed to grow on mannitol, grew very slowly on glycerol and fructose, but grew normally on glucose and gluconate. Group 111 strains were deficient in both NAD- and NADP-linked glucose-6-phosphate dehydrogenase activities that reside in a single enzyme species. 6-Phosphogluconate appeared to be the inductive effector for this enzyme, which was not required for aerobic growth on glucose or gluconate. A single mannitol-negative mutant in group IV also failed to grow on glycerol and glucose, but no biochemical lesion was identified.

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