TRANSFORMATION OF PHOSPHATES BY FREE-LIVING AND SYMBIOTIC ROOT-NODULEBACTERIA RHIZOBIUM-MELILOTI FOLLOWED BY P-31 NMR-SPECTROSCOPY

Biochemical transformations of low-molecular phosphorus-containing com pounds by alfalfa root-nodule bacteria Rhizobium meliloti strains T 79 8 and CXM 1-48, exhibiting different nitrogen-fixing activities, were studied. Primary steps of metabolism were made clear by measuring the level and protonation state of glucose-6-phosphate (GP) and inorganic phosphorus (P-i) under various conditions of nutrient limitation. The dynamics of aerobic respiration and glycolysis in intact cells and alf alfa root nodules inoculated by bacteria were analyzed by a non-destru ctive method of P-31 NMR Fourier spectroscopy. The kinetics of glycoly tic and oxidative metabolism at a low level of high-energy adenyl nucl eotides pointed to the similarity in phosphate transformation by root nodules and by cells grown aerobically until the late logarithmic stag e. It was demonstrated in vivo that strain CXM 1-48, incapable of nitr ogen fixation, transformed GP to pyruvate at a much lower rate than st rain T 798, which is a highly efficient nitrogen fixer.