The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans....

Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are processes occurring simultaneously under oxygen-limited or anaerobic conditions, where both compete for nitrate and organic carbon. Despite their ecological importance, there has been little investigation of how denitrification and DNRA potentials and related functional genes vary vertically with sediment depth. Nitrate ...

During anaerobic growth, Escherichia coli can reduce phosphomolybdate. The reduction can also be carried out by washed cells suspended in buffer at pH 5.7. Phosphate, molybdate, glucose, cells, and anaerobic conditions are required. Reduction is inhibited by 200 microM chromate, 290 microM nitrite, 10 mM tungstate, or 20 mM cysteine. Wild-type (chl+) cells are inhibited by addition of 200 micro...

The effects of CO(2)-limited photosynthesis on (15)NO(3) (-) uptake and reduction by maize (Zea mays, DeKalb XL-45) seedlings were examined in relation to concurrent effects of CO(2) stress on carbohydrate levels and in vitro nitrate reductase activities. During a 10-hour period in CO(2)-depleted air (30 microliters of CO(2)/ per liter), cumulative (15)NO(3) (-) uptake and reduction were restri...

In leaves of spinach plants (Spinacia oleracea L.) performing CO(2) and NO(3) (-) assimilation, at the time of sudden darkening, which eliminates photosystem I-dependent nitrite reduction, only a minor temporary increase of the leaf nitrite content is observed. Because nitrate reduction does not depend on redox equivalents generated by photosystem I activity, a continuation of nitrate reduction...

Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing n...

The requirement of light for the reduction of nitrate by higher plants has been under investigation for sonme time. Burstronm (2) obtained evidence that wheat leaves would reduce nitrate in the light but not in the dark. He concluded that nitrate reduction was directly linked to a photochemical reaction, or that it occurred concomitantly with the fixation and reduction of carbon dioxide. In con...

Intertidal marshes are alternately exposed and submerged due to periodic ebb and flood tides. The tidal cycle is important in controlling the biogeochemical processes of these ecosystems. Intertidal sediments are important hotspots of dissimilatory nitrate reduction and interacting nitrogen cycling microorganisms, but the effect of tides on dissimilatory nitrate reduction, including denitrifica...