Glutamate as a Carbon Source for N2-Fixing Bacteroids Prepared from Soybean Root Nodules

Alanine, not ammonia, is excreted from N2-fixing soybean nodule bacteroids.

Symbiotic nitrogen fixation, the process whereby nitrogen-fixing bacteria enter into associations with plants, provides the major source of nitrogen for the biosphere. Nitrogenase, a bacterial enzyme, catalyzes the reduction of atmospheric dinitrogen to ammonium. In rhizobia-leguminous plant symbioses, the current model of nitrogen transfer from the symbiotic form of the bacteria, called a bact...

Carbon Partitioning in Nitrogen-fixing Root Nodules

The Oxidative Properties of Mitochondria and Bacteroids from Root Nodules of Soybean Treated with Organic Acids

Nodule mitochondria are highly sensitive to the respiratory inhibitor antimycine A. The antimycine-resistant oxygen uptake is 5–10% of the rate of control mitochondrial respiration. The high sensitivity to this inhibitor means that non-phosphorilating pathways are absent from the nodules and the energetic effectiveness of mitochondria is very high. The latter is proved by the good respiratory c...

Isolation of bacteria, transforming bacteria, and bacteroids from soybean nodules.

Postnuclei supernatant of soybean (Glycine max cv. Chippewa 64) nodule homogenate was fractionated by stepwise sucrose density gradient centrifugation into supernatant, endoplasmic reticulum and mitochondria, and three distinct bands with 1.22, 1.25, and 1.27 g/cm(3) of peak density. Based on their enzymic activities, composition of electron transport components, and ultrastructural characteris...

Properties of the nitrogenase system in cell-free extracts of bacteroids from soybean root nodules.

The capacity of excised nodules from soybean plants to fix atmospheric N2 was demonstrated convincingly in 19521 by use of the sensitive '5N technique. Although the specific inhibitory effect of H2 on N2 fixation by nodulated red clover was discovered thirty years ago,2' 3 an understanding of the biochemistry of N2 fixation in symbionts has been delayed as a result of difficulties in obtaining ...