Effects of oxygen on each step of denitrification on Pseudomonas nautica

1989 ◽  
Vol 35 (11) ◽  
pp. 1061-1064 ◽  
Author(s):  
P. Bonin ◽  
M. Gilewicz ◽  
J. C. Bertrand
Keyword(s):  
Nitrous Oxide ◽  
Nitrate Reductase ◽  
Oxygen Concentration ◽  
Nitrite Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
A Value ◽  
Nitrite Reductase Activity ◽  
Effect Of Oxygen

Studies on the effect of oxygen on denitrification have shown that denitrification on Pseudomonas nautica 617 can take place in the presence of oxygen. The enzymes associated with denitrification are affected differently with respect to oxygen concentration. Nitrate reductase was less sensitive toward oxygen than nitrite and nitrous oxide reductases. Nitrate reductase activity was completely blocked at an oxygen concentration greater than 4.05 mg/L, compared with 2.15 and 0.25 mg/L for nitrite and nitrous oxide reductases, respectively. After an aerobic–anaerobic shift, nitrate reductase activity remained unchanged whereas the rate of nitrite reductase activity rose to a value only 20% that of the original rate.Key words: denitrification, oxygen, Pseudomonas.

scholarly journals Effect of tungsten on nitrate and nitrite reductases in Azospirillum brasilense Sp7

1991 ◽  
Vol 37 (10) ◽  
pp. 744-750 ◽  
Author(s):  
Christian Chauret ◽  
Roger Knowles
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Azospirillum Brasilense ◽  
Nitrate Reductase Activity ◽  
Paracoccus Denitrificans ◽  
Reductase Activity ◽  
Whole Cells ◽  
Azospirillum Brasilense Sp7 ◽  
Nitrite Reductase Activity ◽  
Nitrate And Nitrite

Tungstate, at concentrations that completely suppressed nitrate reductase activity in Paracoccus denitrificans, caused only partial inhibition of nitrate reductase in Azospirillum brasilense Sp7. Nitrate reductase activity in cell-free extracts was much more sensitive than whole cells to tungstate, suggesting that there may be a barrier to its transport. Nitrite reductase activity was partially inhibited by tungstate in both whole cells and cell-free extracts. Azospirillum brasilense apparently scavenged enough contaminating molybdenum from molybdenum-limited medium to allow maximum nitrate reductase activity, which was not stimulated by added molybdate. Cells grown in molybdenum-depleted medium could not reduce nitrate. Nitrate concentrations less than 0.25 mM inhibited activity, but not synthesis, of nitrite reductase and caused significant accumulation of nitrite during reduction of nitrate. Key words: Azospirillum brasilense, Paracoccus denitrificans, nitrate reductase, nitrite reductase, tungsten, molybdenum, denitrification.

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.

scholarly journals Nitrogen and Oxygen Regulation of Bacillus subtilis nasDEF Encoding NADH-Dependent Nitrite Reductase by TnrA and ResDE

1998 ◽  
Vol 180 (20) ◽  
pp. 5344-5350 ◽  
Author(s):  
Michiko M. Nakano ◽  
Tamara Hoffmann ◽  
Yi Zhu ◽  
Dieter Jahn
Keyword(s):  
Bacillus Subtilis ◽  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Nitrogen Limitation ◽  
Reductase Activity ◽  
Anaerobic Respiration ◽  
Regulatory System ◽  
Nitrate Respiration ◽  
Nitrite Reductase Activity ◽  
Nitrate And Nitrite

ABSTRACT The nitrate and nitrite reductases of Bacillus subtilishave two different physiological functions. Under conditions of nitrogen limitation, these enzymes catalyze the reduction of nitrate via nitrite to ammonia for the anabolic incorporation of nitrogen into biomolecules. They also function catabolically in anaerobic respiration, which involves the use of nitrate and nitrite as terminal electron acceptors. Two distinct nitrate reductases, encoded bynarGHI and nasBC, function in anabolic and catabolic nitrogen metabolism, respectively. However, as reported herein, a single NADH-dependent, soluble nitrite reductase encoded by the nasDE genes is required for both catabolic and anabolic processes. The nasDE genes, together with nasBC(encoding assimilatory nitrate reductase) and nasF(required for nitrite reductase siroheme cofactor formation), constitute the nas operon. Data presented show that transcription of nasDEF is driven not only by the previously characterized nas operon promoter but also from an internal promoter residing between the nasC andnasD genes. Transcription from both promoters is activated by nitrogen limitation during aerobic growth by the nitrogen regulator, TnrA. However, under conditions of oxygen limitation,nasDEF expression and nitrite reductase activity were significantly induced. Anaerobic induction of nasDEFrequired the ResDE two-component regulatory system and the presence of nitrite, indicating partial coregulation of NasDEF with the respiratory nitrate reductase NarGHI during nitrate respiration.

Isotopic Fractionation During Reduction of Nitrate and Nitrite by Extracts of Spinach Leaves

1985 ◽  
Vol 12 (6) ◽  
pp. 631 ◽  
Author(s):  
SF Ledgard ◽  
KC Woo ◽  
FJ Bergersen
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Spinacia Oleracea ◽  
Reductase Activity ◽  
Isotopic Fractionation ◽  
Cytosolic Extract ◽  
Nitrite Reductase Activity ◽  
Reconstituted System ◽  
No2 Reduction ◽  
Nitrate And Nitrite

The isotopic fractionations of nitrogen during the reduction of NO3- and NO2- in a cytosolic fraction and in a chloroplast preparation from spinach (Spinacia oleracea L.) leaves were determined. The reduction of NO3- to NH3 was studied using a reconstituted system containing cytosolic extract and intact chloroplasts, while a chloroplast system was used for NO2- reduction. In the reconstituted systems the ratio of nitrate reductase activity to nitrite reductase activity had a large effect on the relative amounts of NO2- and NH3 formed. Ammonia predominated when the nitrate reductase to nitrite reductase activity ratio was 1 : 5 and this ratio was used in the isotopic fractionation studies. Significant isotopic fractionation of N was observed in the reconstituted system but not in the chloroplast system. This indicates that the observed isotopic fractionation was associated with the reduction of NO3- to NO2- by nitrate reductase. The isotopic fractionation (i.e. δ15Nproduct - δ15Nsubstrate) for this reaction was - 15‰.

Short-term effects of nitrate on nitrate reductase activity and symbiotic dinitrogen fixation in faba bean and pea

1988 ◽  
Vol 66 (8) ◽  
pp. 1639-1645 ◽  
Author(s):  
Francois-P. Chalifour ◽  
Louise M. Nelson
Keyword(s):  
Nitrate Reductase ◽  
Faba Bean ◽  
Nitrite Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Inhibitory Effects ◽  
Short Term ◽  
Pisum Sativum L ◽  
Vicia Faba L ◽  
Legume Symbiosis

The effects of a short-term supply of combined nitrogen (N) on the Rhizobium–legume symbiosis were studied in faba bean (Vicia faba L.) and pea (Pisum sativum L.) nodulated by R. leguminosarum biovar viceae isolate 175F5 or 175F19 and subjected to increasing levels of [Formula: see text] (0, 5, 10, or 20 mol∙m−3) from 28 to 36 days after planting. Trends in N2-fixing activity (acetylene reduction) showed that faba bean was more tolerant to [Formula: see text] than pea with isolate 175F5 but not with isolate 175F19. Nitrite reductase activities in the leaf, root, and nodule cytosol fractions were severalfold higher than nitrate reductase activities for both hosts. The levels of these enzymes in the nodule cytosol, the absence of bacteroid nitrate reductase and the lack of induction of bacteroid nitrite reductase in response to [Formula: see text] addition are consistent with the lack of [Formula: see text] accumulation in nodules of both hosts. Therefore, it is unlikely that the inhibitory effects of [Formula: see text] on N2 fixation are due to [Formula: see text] inhibition of nitrogenase. The relative levels of nitrate reductase activity in the root and nodule cytosol fractions were, respectively, higher and lower in the two faba bean symbioses ([Formula: see text] tolerant) and in the pea–175F5 symbiosis ([Formula: see text] sensitive) than in the pea–175F19 symbiosis ([Formula: see text] tolerant).

scholarly journals The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits

2012 ◽  
Vol 24 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Anna Kołton ◽  
Renata Wojciechowska ◽  
Maria Leja
Keyword(s):  
Nitrate Reductase ◽  
Nitrogen Metabolism ◽  
Nitrite Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Red Pepper ◽  
Ammonium Ion ◽  
Light Conditions ◽  
Nitrogen Forms ◽  
Ammonium Ions

Abstract The ‘Spartacus’ F1 sweet pepper was grown in a plastic tunnel on rockwool during 2006-2008. A fertigation technique was used for water and fertiliser application. The tunnel was divided into two parts covered with different plastic films. The first part of the tunnel was covered with a film that transmitted less light than the film covering the second part. In both parts of the tunnel, the plants were divided into two groups. One group of plants was fertilised with just nitrate nitrogen (100% N-NO3) and the other one with three forms of nitrogen (N-NO3:N-NH4:N-NH2 in a ratio of 50:13:37). Fruits were harvested mature green and red. Concentrations of nitrate and ammonium ions as well as total nitrogen and free amino acids were analysed in the plant material. Nitrate and nitrite reductase activities were also investigated, and dry matter content and soluble sugars were also determined. Higher light intensity increased nitrate concentration in red pepper fruits but decreased ammonium ion content. These tendencies were not as obvious in green fruits. In most cases, red fruits fertilised with three nitrogen forms accumulated more nitrates than those fertilised with N-NO3. This observation was similar in the case of green fruits. In most cases, pepper fruits accumulated more ammonium ions in the case of N-NO3 fertilisation than when three forms of nitrogen were applied, but the differences were not always statistically significant. Higher nitrate reductase activity was observed in the case of better light conditions as well as mixed nitrogen fertilisation in red pepper fruits. No differences were observed in the case of nitrite reductase activity between fruits harvested from various treatments in red and also green fruits, with some exceptions. The green fruits of pepper had higher nitrate reductase activity than the red ones. It can be summarised that various light conditions influenced the nitrogen metabolism of pepper fruits as well as the different nitrogen forms applied with fertilisers.

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