scholarly journals Nitrate reduction and nitrogen fixation in symbiotic association Rhizobium-legumes.

2002 ◽  
Vol 49 (2) ◽  
pp. 537-546 ◽  
Author(s):  
Robert Luciński ◽  
Władysław Polcyn ◽  
Lech Ratajczak
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Gas Diffusion ◽  
Review Literature ◽  
Diffusion Resistance ◽  
Symbiotic Association ◽  
Symbiotic Associations ◽  
Legume Plants

The inhibitory effect of nitrate on nitrogenase activity in root nodules of legume plants has been known for a long time. The major factor inducing changes in nitrogenase activity is the concentration of free oxygen inside nodules. Oxygen availability in the infected zone of nodule is limited, among others, by the gas diffusion resistance in nodule cortex. The presence of nitrate may cause changes in the resistance to O2 diffusion. The aim of this paper is to review literature data concerning the effect of nitrate on the symbiotic association between rhizobia and legume plants, with special emphasis on nitrogenase activity. Recent advances indicate that symbiotic associations of Rhizobium strains characterized by a high nitrate reductase activity are less susceptible to inhibition by nitrate. A thesis may be put forward that dissimilatory nitrate reduction, catalyzed by bacteroid nitrate reductase, significantly facilitates the symbiotic function of bacteroids.

Voltammetric characterization of the aerobic energy-dissipating nitrate reductase of Paracoccus pantotrophus: exploring the activity of a redox-balancing enzyme as a function of electrochemical potential

2007 ◽  
Vol 409 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Andrew J. Gates ◽  
David J. Richardson ◽  
Julea N. Butt
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Reductase Activity ◽  
Electrochemical Potential ◽  
Intact Cells ◽  
Protein Film ◽  
Protein Film Voltammetry ◽  
Voltammetric Studies ◽  
Paracoccus Pantotrophus

Paracoccus pantotrophus expresses two nitrate reductases associated with respiratory electron transport, termed NapABC and NarGHI. Both enzymes derive electrons from ubiquinol to reduce nitrate to nitrite. However, while NarGHI harnesses the energy of the quinol/nitrate couple to generate a transmembrane proton gradient, NapABC dissipates the energy associated with these reducing equivalents. In the present paper we explore the nitrate reductase activity of purified NapAB as a function of electrochemical potential, substrate concentration and pH using protein film voltammetry. Nitrate reduction by NapAB is shown to occur at potentials below approx. 0.1 V at pH 7. These are lower potentials than required for NarGH nitrate reduction. The potentials required for Nap nitrate reduction are also likely to require ubiquinol/ubiquinone ratios higher than are needed to activate the H+-pumping oxidases expressed during aerobic growth where Nap levels are maximal. Thus the operational potentials of P. pantotrophus NapAB are consistent with a productive role in redox balancing. A Michaelis constant (KM) of approx. 45 μM was determined for NapAB nitrate reduction at pH 7. This is in line with studies on intact cells where nitrate reduction by Nap was described by a Monod constant (KS) of less than 15 μM. The voltammetric studies also disclosed maximal NapAB activity in a narrow window of potential. This behaviour is resistant to change of pH, nitrate concentration and inhibitor concentration and its possible mechanistic origins are discussed.

Phenotypic reversion of nitrogenase in pleiotropic mutants of Rhizobium meliloti

1979 ◽  
Vol 25 (3) ◽  
pp. 298-301 ◽  
Author(s):  
Ilona Barabás ◽  
Tibor Sik
Keyword(s):  
Amino Acids ◽  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Amino Acid Utilization ◽  
Phenotypic Reversion

In two out of three pleiotropic mutants of Rhizobium meliloti, defective in nitrate reductase induced by amino acid utilization in vegetative bacteria and in symbiotic nitrogen fixation, nitrogenase activity could be restored completely by purines and partially by the amino acids L-glutamate, L-aspartate, L-glutamine, and L-asparagine. The compounds restoring effectiveness in nitrogen fixation did not restore nitrate reductase activity in vegetative bacteria. The restoration of effectiveness supports our earlier conclusion that the mutation is not in the structural gene for a suggested common subunit of nitrogenase and nitrate reductase.

Differential effects of ozone on in vivo nitrate reduction in soybean cultivars. I. Response to exogenous sugars

1978 ◽  
Vol 56 (13) ◽  
pp. 1540-1544 ◽  
Author(s):  
Albert C. Purvis
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Foliar Injury ◽  
Glycolytic Intermediates ◽  
Glycine Max L ◽  
Growth Chambers ◽  
Visible Foliar Injury

Two cultivars of soybeans (Glycine max (L.) Merr.) differing widely in their resistance to ozone were exposed to 0.5 μl/ℓ ozone for 2 h in growth chambers. In vivo nitrate reduction was depressed by more than 50% in the primary leaves of Dare, the ozone-sensitive cultivar, but was not significantly altered in Hood, the ozone-resistant cultivar. Sucrose, up to 1.5% (w/v), added to excised seedlings of the Dare cultivar during exposure to ozone eliminated the ozone depression of in vivo nitrate reductase activity and also reduced foliar injury. Addition of two glycolytic intermediates, glyceraldehyde-3-phosphate and fructose-1,6-diphosphate, to the infiltration medium recovered some in vivo nitrate reduction in treated Dare leaves. The levels of extractable nitrate reductase and glyceraldehyde-3-phosphate dehydrogenase in the primary leaves of both cultivars were unaltered by ozone fumigations. These observations led to the conclusion that ozone depression of in vivo nitrate reduction is not due to ozone inactivation of nitrate reductase or of the enzymes coupling nitrate reduction to glycolysis, but may be caused by an inadequate supply of photosynthetic sugars. It was also noted that ozone depression of in vivo nitrate reduction only occurred with treatments which subsequently caused the development of visible foliar injury.

scholarly journals Respiratory Nitrate Ammonification by Shewanella oneidensis MR-1

2006 ◽  
Vol 189 (2) ◽  
pp. 656-662 ◽  
Author(s):  
Claribel Cruz-García ◽  
Alison E. Murray ◽  
Joel A. Klappenbach ◽  
Valley Stewart ◽  
James M. Tiedje
Keyword(s):  
Nitrous Oxide ◽  
Nitrate Reductase ◽  
Electron Acceptor ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Shewanella Oneidensis ◽  
Gene Encoding ◽  
Nitrate Ammonification ◽  
Sequential Reduction

ABSTRACT Anaerobic cultures of Shewanella oneidensis MR-1 grown with nitrate as the sole electron acceptor exhibited sequential reduction of nitrate to nitrite and then to ammonium. Little dinitrogen and nitrous oxide were detected, and no growth occurred on nitrous oxide. A mutant with the napA gene encoding periplasmic nitrate reductase deleted could not respire or assimilate nitrate and did not express nitrate reductase activity, confirming that the NapA enzyme is the sole nitrate reductase. Hence, S. oneidensis MR-1 conducts respiratory nitrate ammonification, also termed dissimilatory nitrate reduction to ammonium, but not respiratory denitrification.

Nitrate reduction and nitrogenase activity in Spirillum lipoferum

1977 ◽  
Vol 23 (3) ◽  
pp. 306-310 ◽  
Author(s):  
Carlos A. Neyra ◽  
Peter Van Berkum
Keyword(s):  
Nitrate Reduction ◽  
Time Course ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Nitrite Reduction ◽  
Lag Phase ◽  
Nitrite Accumulation ◽  
Assimilatory Nitrate Reduction ◽  
Nitrate And Nitrite ◽  
Anaerobic Pretreatment

Nitrate and nitrite reduction under aerobic, microaerophillic, and anaerobic conditions was demonstrated in Spirillum lipoferum (ATCC 29145). Nitrite did not accumulate during assimilatory nitrate reduction in air. The nitrite produced during dissimilatory nitrate reduction accumulated in the medium but not in the cells. On exposure of the bacteria to nitrate and anaerobiosis, a low initial rate (lag) was followed by accelerated rates of nitrite accumulation. A 3-h anaerobic pretreatment, in the absence of nitrate, did not avoid the lag phase. No nitrate reductase activity (NRA) developed in the presence of chloramphenicol. The data suggest that induction of anaerobic NRA in S. lipoferum required nitrate and protein synthesis.Anaerobic N2ase activity by S. lipoferum was greatly stimulated in the presence of nitrate. The time course of nitrate reduction was coincidental with the pattern of nitrate-stimulated N2ase activity indicating that a relationship exists between these two processes.

scholarly journals Nitrate reduction mutants of fusarium moniliforme (gibberella fujikuroi).

Genetics ◽  
1988 ◽  
Vol 118 (3) ◽  
pp. 417-423
Author(s):  
C Klittich ◽  
J F Leslie
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Fusarium Moniliforme ◽  
Reductase Activity ◽  
Regulatory Gene ◽  
Resistant Mutant ◽  
Gibberella Fujikuroi ◽  
Mutant Type ◽  
Nit Mutants ◽  
Chlorate Resistant Mutant

Abstract Twelve strains of Fusarium moniliforme were examined for their ability to sector spontaneously on toxic chlorate medium. All strains sectored frequently; 91% of over 1200 colonies examined formed chlorate-resistant, mutant sectors. Most of these mutants had lesions in the nitrate reduction pathway and were unable to utilize nitrate (nit mutants). nit mutations occurred in seven loci: a structural gene for nitrate reductase (nit1), a regulatory gene specific for the nitrate reduction pathway (nit3), and five genes controlling the production of a molybdenum-containing cofactor that is necessary for nitrate reductase activity (nit2, nit4, nit5, nit6, nit7). No mutations affecting nitrite reductase or a major nitrogen regulatory locus were found among over 1000 nit mutants. Mutations of nit1 were recovered most frequently (39-66%, depending on the strain) followed by nit3 mutations (23-42%). The frequency of isolation of each mutant type could be altered, however, by changing the source of nitrogen in the chlorate medium. We concluded that genetic control of nitrate reduction in F. moniliforme is similar to that in Aspergillus and Neurospora, but that the overall regulation of nitrogen metabolism may be different.

Nitrate reductase activities of rhizobia and the correlation between nitrate reduction and nitrogen fixation

1979 ◽  
Vol 25 (10) ◽  
pp. 1169-1174 ◽  
Author(s):  
James R. Manhart ◽  
Peter P. Wong
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Root Nodules ◽  
Sole Source ◽  
Rhizobium Japonicum ◽  
Rhizobium Trifolii ◽  
Rhizobium Species

All species of Rhizobium except R. lupini had nitrate reductase activity. Only R. lupini was incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species of Rhizobium. Rhizobium japonicum and some Rhizobium species of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate. Rhizobium trifolii, R. phaseoli, and R. legnminosarum did not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids of R. japonicum and some strains of cowpea Rhizobium, high N2 fixation activities were accompanied by high nitrate reductase activities. In bacteroids of R. trifolii, R. leguminosarum, and R. phaseoli, high N2 fixation activities were not accompanied by high nitrate reductase activities.

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