Bacteria, nitrogen-fixing

A number of nitrogen-fixing bacteria contain vanadium and it has been shown that in one of these, Azotobacter, there are three distinct nitrogenase systems based in turn on Mo, V and Fe, each of which has an underlying functional and structural similarity.This discovery has prompted a search for models and the brown compound [Na(thf)]+[V(N2)2(dppe)2] (dppe = Pli2PCH2CH2PPh2) has recently been prepared by reduction of VCI3 by sodium naphthalenide... 

Nitrogen fixation takes place in a wide variety of bacteria, the best known of which is rhizobium which is found in nodules on the roots of leguminous plants such as peas, beans, soya and clover. The essential constituents of this and all other nitrogen-fixing bacteria are ... 

C14-0026. Nitrogen-fixing bacteria react N2 with H2 O to produce NH3 and O2 using ATP as their energy source. About 24 molecules of ATP are consumed per molecule of N2 fixed. What percentage of the free energy derived from ATP is stored in NH3 ... 

Fallik E, Y-K Chan, RL Robson (1991) Detection of alternative nitrogenases in aerobic gram-negative nitrogen-fixing bacteria. J Bacteriol 173 365-371. 

K. J. Lee and M. H. Gaskins, Increased root exudation of C-compounds by sorghum. seedlings inoculated with nitrogen-fixing bacteria. Plant and Soil 69 391 (1982). 

Molybdenum is essential for a number of enzymes, for example xanthine oxidases in mammals and nitrogenases in nitrogen-fixing bacteria. 

Diazotrophs Nitrogen-fixing bacteria. In the marine environment, some nitrogen fixers live as symbionts in phytoplankton, particularly diatoms. 

Bacterial ferredoxins function primarily as electron carriers in ferredoxin-mediated oxidation reduction reactions. Some examples are reduction of NAD, NADP, FMN, FAD, sulfite and protons in anaerobic bacteria, CO -fixation cycles in photosynthetic bacteria, nitrogen fixation in anaerobic nitrogen fixing bacteria, and reductive carboxylation of substrates in fermentative bacteria. The roles of bacterial ferredoxins in these reactions have been summarized by Orme-Johnson (2), Buchanan and Arnon (3), and Mortenson and Nakos (31). 

Flavonoid levels in plants can be affected by their nutritional status. Low nitrate concentrations, for example, induce flavonoid accumulation, which then serve as chemoattractants to nitrogen-fixing bacteria. Nodulation then restores the nitrogen economy of the plant.In L. pedunculatus, proanthocyanidins are not formed under high-nitrogen conditions, presumably because the requirement for nodulation is not so critical. 

Only certain prokaryotes can fix atmospheric nitrogen. These include the cyanobacteria of soils and fresh and salt waters, other kinds of free-living soil bacteria such as Azotobacter species, and the nitrogen-fixing bacteria that live as symbionts in the root nodules of leguminous plants. The first important product of nitrogen fixation is ammonia, which can be used by all organisms either directly or after its conversion to other soluble compounds such as nitrites, nitrates, or amino acids. 

The symbiotic relationship between leguminous plants and the nitrogen-fixing bacteria in their root... 

---