Nitrogen fixation by Klebsiella grown in the presence of oxygen

1972 ◽  
Vol 18 (12) ◽  
pp. 1845-1850 ◽  
Author(s):  
Robert Klucas
Keyword(s):  
Nitrogen Fixation ◽  
Dissolved Oxygen ◽  
Nitrogenase Activity ◽  
Fixed Nitrogen ◽  
Submerged Cultures ◽  
Continuous Cultures ◽  
Dissolved Oxygen Tension ◽  
Whole Cells ◽  
Oxygen Effects ◽  
Oxygen Tensions

Several facultative asymbiotic N2-fixing bacteria exhibited nitrogenase activity when grown in the presence of air and a limiting amount of fixed nitrogen. One isolate (S-4) identified as Klebsiella was examined in more detail for oxygen effects. Nitrogenase was not detectable in highly aerated submerged cultures but was detectable in shaken and continuous cultures at dissolved oxygen tensions of 3 and 10 mm of Hg respectively. No nitrogenase activity was found in cells from continuous cultures maintained at a dissolved oxygen tension of 15 mm of Hg or above. The nitrogenase activity in whole cells was not oxygen dependent but was oxygen tolerant.

scholarly journals Anabaena sp. Strain PCC 7120 Gene devH Is Required for Synthesis of the Heterocyst Glycolipid Layer

2005 ◽  
Vol 187 (7) ◽  
pp. 2326-2331 ◽  
Author(s):  
Martha E. Ramírez ◽  
Pratibha B. Hebbar ◽  
Ruanbao Zhou ◽  
C. Peter Wolk ◽  
Stephanie E. Curtis
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Regulatory Protein ◽  
Protein A ◽  
Filamentous Cyanobacterium ◽  
Fixed Nitrogen ◽  
Ultrastructural Studies ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Mutant Forms

ABSTRACT In response to deprivation for fixed nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 provides a microoxic intracellular environment for nitrogen fixation through the differentiation of semiregularly spaced vegetative cells into specialized cells called heterocysts. The devH gene is induced during heterocyst development and encodes a product with characteristics of a trans-acting regulatory protein. A devH mutant forms morphologically distinguishable heterocysts but is Fox−, incapable of nitrogen fixation in the presence of oxygen. We demonstrate that rearrangements of nitrogen fixation genes take place normally in the devH mutant and that it is Fix+, i.e., has nitrogenase activity under anoxic conditions. The Fox− phenotype was shown by ultrastructural studies to be associated with the absence of the glycolipid layer of the heterocyst envelope. The expression of glycolipid biosynthetic genes in the mutant is greatly reduced, and heterocyst glycolipids are undetectable.

scholarly journals Nitrogen Fixation and Hydrogen Metabolism in Relation to the Dissolved Oxygen Tension in Chemostat Cultures of the Wild Type and a Hydrogenase-Negative Mutant of Azorhizobium caulinodans

1994 ◽  
Vol 60 (6) ◽  
pp. 1859-1866 ◽  
Author(s):  
Fred C. Boogerd ◽  
Marijke M. A. Ferdinandy-van Vlerken ◽  
Crispen Mawadza ◽  
Annemieke F. Pronk ◽  
Adriaan H. Stouthamer ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Dissolved Oxygen ◽  
Oxygen Tension ◽  
Hydrogen Metabolism ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Dissolved Oxygen Tension ◽  
Chemostat Cultures ◽  
Negative Mutant

scholarly journals Importance of cis Determinants and Nitrogenase Activity in Regulated Stability of the Klebsiella pneumoniae Nitrogenase Structural Gene mRNA

1999 ◽  
Vol 181 (12) ◽  
pp. 3751-3760 ◽  
Author(s):  
Holly M. Simon ◽  
Mark M. Gosink ◽  
Gary P. Roberts
Keyword(s):  
Nitrogen Fixation ◽  
Simple Model ◽  
Klebsiella Pneumoniae ◽  
Mrna Stability ◽  
Nitrogenase Activity ◽  
Expression System ◽  
Fixed Nitrogen ◽  
Complicated Model ◽  
A Site ◽  
Gene Mrna

ABSTRACT The Klebsiella pneumoniae nitrogen fixation (nif) mRNAs are unusually stable, with half-lives of 20 to 30 min under conditions favorable to nitrogen fixation (limiting nitrogen, anaerobiosis, temperatures of 30°C). Addition of O2 or fixed nitrogen or temperature increases to 37°C or more result in the dramatic destabilization of the nifmRNAs, decreasing the half-lives by a factor of 3 to 5. A plasmid expression system, independent of nif transcriptional regulation, was used to define cis determinants required for the regulated stability of the 5.2-kb nifHDKTY mRNA and to test the model suggested by earlier work that NifA is required in trans to stabilize nif mRNA undernif-derepressing conditions. O2 regulation ofnifHDKTY mRNA stability is impaired in a plasmid containing a deletion of a 499-bp region of nifH, indicating that a site(s) required for the O2-regulated stability of the mRNA is located within this region. The simple model suggested from earlier work that NifA is required for stabilizingnif mRNA under conditions favorable for nitrogen fixation was disproved, and in its place, a more complicated model involving the sensing of nitrogenase activity as a component of the system regulating mRNA stability is proposed. Analysis ofnifY mutants and overexpression suggests a possible involvement of the protein in this sensing process.

The fixed nitrogen sensitivity of biological nitrogen fixation in salt marshes sediments from the northeastern United States

2020 ◽  
Author(s):  
Romain Darnajoux ◽  
Rei Zhang ◽  
Katja Luxem ◽  
Xinning Zhang
Keyword(s):  
Nitrogen Fixation ◽  
Salt Marshes ◽  
Biological Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Inorganic Nitrogen ◽  
Ammonium Concentration ◽  
Desulfovibrio Vulgaris ◽  
Fixed Nitrogen ◽  
Sulfate Reducing ◽  
Biological Nitrogen

<p>Biological nitrogen fixation, the main input of fixed N into ecosystems, converts inert N<sub>2</sub> gas into bioavailable ammonium in an energetically costly reaction catalyzed by the prokaryotic metalloenzyme nitrogenase.  The high ATP and reductant requirements of N<sub>2</sub> fixation explain why this process is highly regulated in diazotrophs, with the presence of ammonium inhibiting nitrogenase expression and activity. Yet, several reports of N<sub>2</sub> fixation in ammonium- and nitrate-rich (10 to 300 µM) benthic environments challenge our understanding of a key environmental sensitivity of N<sub>2</sub> fixation. Field studies point to heterotrophic sulfate reducers as the likely diazotrophs in these benthic settings, but the fixed N sensitivity of sulfate-reducing diazotrophs is not well understood due to a dearth of culture studies. Additionally, assays of N<sub>2</sub> fixation in incubations rarely involve parallel measurements of dissolved inorganic nitrogen, possibly leading to experimental bias in favor of detecting activity under ammonium-replete initial conditions.</p><p>To help reconcile the environmental results, we investigate the ammonium sensitivity of N<sub>2</sub> fixation using the acetylene reduction assay and <sup>15</sup>N<sub>2</sub> tracer methods in i) the model sulfate-reducing diazotroph, <em>Desulfovibrio vulgaris</em> str. Hildenborough (DvH), ii) four enrichment cultures from salt marsh sediments of New Jersey, and iii) slurry incubations of sediments collected from three northeastern salt marshes. In all instances, we found that ammonium strongly inhibits biological nitrogen fixation, with nitrogenase activity only detectable when ammonium concentration is below a threshold of 10 µM (slurry incubation) or 2 µM (pure cultures, enrichments). Amendment of ammonium quickly inhibits nitrogen fixation and nitrogenase activity only resumes  once ammonium is depleted to the threshold level. Ammonium additions to actively fixing samples show complete inhibition of N<sub>2</sub> fixation within several hours post-addition. </p><p>Our measurements of the ammonium sensitivity of benthic N<sub>2</sub> fixation are consistent with the traditional understanding of nitrogen fixer metabolism and with early findings of Postgate et al. (1984) demonstrating that N<sub>2</sub> fixation by the sulfate reducer <em>Desulfovibrio gigas</em> is inhibited by ammonium levels that exceed 10 µM. These results help clarify a long-standing paradox in benthic nitrogen cycling. We suggest that prior observations of N<sub>2</sub> fixation at elevated ammonium levels could reflect methodological artifacts due to very fast depletion of ammonium during activity assays, legacy N<sub>2</sub> fixation activity associated with incomplete inhibition by ammonium, or spatial heterogeneity. Further work to standardize fixed N sensitivity assays could help with cross-study comparisons and with clarifying inconsistencies in our understanding of how environmental fixed nitrogen levels control nitrogen fixation.</p>

Effect of oxygen on batch and continuous cultures of a nitrogen-fixing Arthrobacter sp.

1979 ◽  
Vol 25 (6) ◽  
pp. 746-751 ◽  
Author(s):  
Isabella Cacciari ◽  
Daniela Lippi ◽  
Lucien M. Bordeleau
Keyword(s):  
Respiration Rate ◽  
Acetylene Reduction ◽  
Respiratory Activity ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Anaerobic Conditions ◽  
Continuous Cultures ◽  
Partial Pressures ◽  
Oxygen Tensions ◽  
Effect Of Oxygen

Growth, acetylene reduction, and respiration rate were studied in batch and continuous cultures of Arthrobacter fluorescens at different oxygen partial pressures. The optimum pO2 values for growth and acetylene reduction were 0.05 and 0.025 atm, respectively, but microorganisms can tolerate higher pO2 values. The growth of cultures provided with combined nitrogen was dependent on oxygen availability, and strict anaerobic conditions did not support growth. Acetylene reduction of a population grown in continuous culture and adapted to low pO2 (0.02 atm) was much more sensitive to oxygenation than that of a population adapted to high pO2 (0.4 atm). Their maximum nitrogenase activity, at their optimal pO2 values, were quite different. The respiratory activity of nitrogen-fixing cultures increased with increasing oxygen tensions until a pO2 of 0.2 atm. At higher pO2 values, the respiration rate began to decrease.

Nodulation and nitrogen fixation by red alder and Sitka alder on coal mine spoils

1982 ◽  
Vol 12 (4) ◽  
pp. 992-997 ◽  
Author(s):  
Paul Heilman ◽  
Gorden Ekuan
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Douglas Fir ◽  
Tree Age ◽  
Fixed Nitrogen ◽  
Red Alder ◽  
Mine Spoils ◽  
Nodule Number ◽  
Western Washington ◽  
The Difference

Nodule number, nodule weight, and nitrogen fixation (nitrogenase activity by acetylene reduction) were determined for 3 years for red alder (Alnusrubra Bong.) and Sitka alder (Alnussinuata Reg. Rydb.) on three types of coal spoils in western Washington. Generally, the two species were similar in number and weight of nodules and in nitrogen-fixation rates when measured in June (these rates varied from 23 to 27 µmol•g−1•h−1). The type of coal spoil material influenced nodule number but not nodule weight. Topsoil covered subsoil had the highest number of nodules. Trees on unweathered subsoil had the lowest number, particularly for Sitka alder. Nodule weight (dry, ash free) varied from 68 kg•ha−1 for 5-year-old Sitka alder interplanted in a 1:1 mix with Douglas-fir (1790 alders•ha−1) to 188–200 kg•ha−1 for pure stands of both alder species at age 5 (5380 trees•ha−1). The difference in nodule weight between species was not significant. Both species fixed nitrogen at similar rates although in the last year of measurement red alder trees fixed 37% more nitrogen than Sitka alder. This difference was not significant, however. Nitrogen fixation per unit area depended on tree age and spacing, varying from 17 kg•ha−1•year−1 at age 3 with 1830 alders•ha−1 to 150 kg•ha−1•year−1 by both species at age 5 and a density of 5380 trees•ha−1. Fixation rates increased from age 3 to 5 years primarily because of increased nodule weight. Nitrogen fixation by the Sitka alder in mixture with Douglas-fir was relatively high and was encouraging for the concept of mixed plantings of these two species. However, response of Douglas-fir to mixed planting with Sitka alder has not been demonstrated.

scholarly journals Effect of Sowing Depth on Nodulation, Nitrogen Fixation, Root and Hypocotyl Growth, and Yield in Groundnut (Arachis hypogaea)

1987 ◽  
Vol 23 (3) ◽  
pp. 283-291 ◽  
Author(s):  
P. T. C. Nambiar ◽  
B. Srinivasa Rao
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Field Experiments ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Growth And Yield ◽  
Fixed Nitrogen ◽  
Hypocotyl Growth ◽  
Hypocotyl Length ◽  
Sowing Depth

SUMMARYHypocotyl length in groundnut is a function of sowing depth. In field experiments deep sowing increased the mass of hypocotyl but decreased that of roots, pods and haulm. Few nodules were formed on the hypocotyls of plants from shallow sown seeds (4–5 cm deep). More hypocotyl nodules occurred on Virginia types when deep sown but the number and activity of nodules on the roots decreased. Nodules on the hypocotyl appeared later and fixed less nitrogen than root nodules. Although hypocotyl nodules fixed nitrogen during the later stages of plant growth, this activity could not compensate for the loss in nitrogenase activity due to deeper sowing. Deeper sowing also resulted in decreased pod yields.

Metabolic regulation of nitrogen fixation in Rhodospirillum rubrum

2006 ◽  
Vol 34 (1) ◽  
pp. 160-161 ◽  
Author(s):  
H. Wang ◽  
A. Norén
Keyword(s):  
Nitrogen Fixation ◽  
Metabolic Regulation ◽  
Rhodospirillum Rubrum ◽  
Nitrogenase Activity ◽  
Nitrogen Concentration ◽  
Sudden Increase ◽  
Fixed Nitrogen ◽  
Energy Depletion ◽  
Adp Ribosylation ◽  
Dinitrogenase Reductase

Nitrogenase activity in Rhodospirillum rubrum is post-translationally regulated by DRAG (dinitrogenase reductase glycohydrolase) and DRAT (dinitrogenase reductase ADP-ribosylation transferase). When a sudden increase in fixed nitrogen concentration or energy depletion is sensed by the cells, DRAG is inactivated and DRAT activated. We propose that the regulation of DRAG is dependent on its location in the cell and the presence of an ammonium-sensing protein.

Studies on compatibility of nitrogen fixation by high-temperature-adapted Rhizobium strains and Vigna radiata genotypes at two moisture levels in calcareous soil

1983 ◽  
Vol 101 (2) ◽  
pp. 377-381 ◽  
Author(s):  
R. Rai ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
High Temperature ◽  
Grain Yield ◽  
Vigna Radiata ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Summer Season ◽  
Green Gram ◽  
Rhizobium Strains

SUMMARYRhizobium strains adapted to high temperature, and genotypes of green gram, were used to study the symbiotic N2-fixation in a summer season at two moisture levels in calcareous soil. Different interactions between strains and genotypes were observedatthe two moisture levels. At both moisture levels, strain S4 with the green gram genotype S8 showed the greatest grain yield, nitrogenase activity, leghaemoglobin and ethanolsoluble carbohydrate of nodules.

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