scholarly journals The kinetics of the reduction of isocyanides, acetylenes and the cyanide ion by nitrogenase preparation from Azotobacter chroococcum and the effects of inhibitors

1968 ◽  
Vol 107 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M Kelly
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Fixation ◽  
Azotobacter Chroococcum ◽  
Nitrogen Fixing ◽  
Cyanide Ion ◽  
Nitrogen Fixing Bacteria ◽  
Methyl Isocyanide ◽  
Kinetics Of

1. Nitrogen-fixing preparations from Azotobacter chroococcum reduced substrates with the following Km values: methyl isocyanide, 1·8×10−4m; ethyl isocyanide, 2·5×10−2m; cyanide ion, 1·4×10−3m; acetylene, 1·2×10−4m. 2. Nitrogen, carbon monoxide or hydrogen competitively inhibited isocyanide reduction with the following Ki values: hydrogen, 1·3×10−3m; carbon monoxide, 6·8×10−6m; nitrogen, 4·3×10−4m. 3. Living nitrogen-fixing bacteria, and isolated clover nodules, formed methane from methyl isocyanide. 4. These results are discussed in relation to other work and possible mechanisms of nitrogen fixation.

scholarly journals Genomic characterization and computational phenotyping of nitrogen-fixing bacteria isolated from Colombian sugarcane fields

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luz K. Medina-Cordoba ◽  
Aroon T. Chande ◽  
Lavanya Rishishwar ◽  
Leonard W. Mayer ◽  
Lina C. Valderrama-Aguirre ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Nitrogen Fixation ◽  
Plant Growth ◽  
Phosphate Solubilization ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Promising Tool ◽  
A Genome ◽  
Plant Growth Promoting ◽  
Growth Promoting

AbstractPrevious studies have shown the sugarcane microbiome harbors diverse plant growth promoting microorganisms, including nitrogen-fixing bacteria (diazotrophs), which can serve as biofertilizers. The genomes of 22 diazotrophs from Colombian sugarcane fields were sequenced to investigate potential biofertilizers. A genome-enabled computational phenotyping approach was developed to prioritize sugarcane associated diazotrophs according to their potential as biofertilizers. This method selects isolates that have potential for nitrogen fixation and other plant growth promoting (PGP) phenotypes while showing low risk for virulence and antibiotic resistance. Intact nitrogenase (nif) genes and operons were found in 18 of the isolates. Isolates also encode phosphate solubilization and siderophore production operons, and other PGP genes. The majority of sugarcane isolates showed uniformly low predicted virulence and antibiotic resistance compared to clinical isolates. Six strains with the highest overall genotype scores were experimentally evaluated for nitrogen fixation, phosphate solubilization, and the production of siderophores, gibberellic acid, and indole acetic acid. Results from the biochemical assays were consistent and validated computational phenotype predictions. A genotypic and phenotypic threshold was observed that separated strains by their potential for PGP versus predicted pathogenicity. Our results indicate that computational phenotyping is a promising tool for the assessment of bacteria detected in agricultural ecosystems.

Endophytic nitrogen fixation – a possible ‘hidden’ source of nitrogen for lodgepole pine trees growing at unreclaimed gravel mining sites

2019 ◽  
Vol 95 (11) ◽  
Author(s):  
Kiran Preet Padda ◽  
Akshit Puri ◽  
Chris Chanway
Keyword(s):  
Nitrogen Fixation ◽  
Lodgepole Pine ◽  
Nifh Gene ◽  
Control Treatment ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Mining Sites ◽  
Greenhouse Study ◽  
Gravel Mining ◽  
Pine Trees

ABSTRACT Lodgepole pine (Pinus contorta var. latifolia) trees have been thriving on unreclaimed gravel mining sites in British Columbia, Canada, with tissue nitrogen-content and growth-rate unaffected by extremely low soil nitrogen-levels. This indicates that pine trees could be accessing a hidden nitrogen source to fulfill their nitrogen requirements – possibly via endophytic nitrogen-fixation. Endophytic bacteria originally isolated from native pine trees growing at gravel sites were selected (n = 14) for in vitro nitrogen-fixation assays and a year long greenhouse study to test the overall hypothesis that naturally occurring endophytic nitrogen-fixing bacteria sustain pine tree growth under nitrogen-limited conditions. Each of the 14 bacteria colonized the internal tissues of pine trees in the greenhouse study and fixed significant amounts of nitrogen from atmosphere (23%–53%) after one year as estimated through 15N isotope dilution assay. Bacterial inoculation also significantly enhanced the length (31%–64%) and biomass (100%–311%) of pine seedlings as compared to the non-inoculated control treatment. In addition, presence of the nifH gene was confirmed in all 14 bacteria. Our results support the possibility that pine trees associate with nitrogen-fixing bacteria, capable of endophytic colonization, to survive at unreclaimed gravel mining pits and this association could potentially be utilized for effective reclamation of highly disturbed sites in a sustainable manner.

scholarly journals Differing Courses of Genetic Evolution of Bradyrhizobium Inoculants as Revealed by Long-Term Molecular Tracing in Acacia mangium Plantations

2014 ◽  
Vol 80 (18) ◽  
pp. 5709-5716 ◽  
Author(s):  
M. M. Perrineau ◽  
C. Le Roux ◽  
A. Galiana ◽  
A. Faye ◽  
R. Duponnois ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Growth Promotion ◽  
Acacia Mangium ◽  
Housekeeping Genes ◽  
Nitrogen Fixing ◽  
Microbial Inoculants ◽  
Nitrogen Fixing Bacteria ◽  
Content Type ◽  
Significant Difference

ABSTRACTIntroducing nitrogen-fixing bacteria as an inoculum in association with legume crops is a common practice in agriculture. However, the question of the evolution of these introduced microorganisms remains crucial, both in terms of microbial ecology and agronomy. We explored this question by analyzing the genetic and symbiotic evolution of twoBradyrhizobiumstrains inoculated onAcacia mangiumin Malaysia and Senegal 15 and 5 years, respectively, after their introduction. Based on typing of several loci, we showed that these two strains, although closely related and originally sampled in Australia, evolved differently. One strain was recovered in soil with the same five loci as the original isolate, whereas the symbiotic cluster of the other strain was detected with no trace of the three housekeeping genes of the original inoculum. Moreover, the nitrogen fixation efficiency was variable among these isolates (either recombinant or not), with significantly high, low, or similar efficiencies compared to the two original strains and no significant difference between recombinant and nonrecombinant isolates. These data suggested that 15 years after their introduction, nitrogen-fixing bacteria remain in the soil but that closely related inoculant strains may not evolve in the same way, either genetically or symbiotically. In a context of increasing agronomical use of microbial inoculants (for biological control, nitrogen fixation, or plant growth promotion), this result feeds the debate on the consequences associated with such practices.

Asymbiotic N2-fixing bacteria associated with three boreal conifers

1984 ◽  
Vol 14 (4) ◽  
pp. 595-597 ◽  
Author(s):  
L. Z. Florence ◽  
F. D. Cook
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Seedling Root ◽  
Natural Stands

Azotobacter spp., Azospirillum spp., and Desulfovibrio spp., were identified as the predominant nitrogen-fixing bacteria associated with seedling root sections collected from natural stands of Pinusbanksiana Lamb., Piceamariana (Mill.) B.S.P., and Larixlaricina (Du Roi) K. Koch growing in Alberta. Samples from the sandy upland habitat of P. banksiana exhibited lower average rates of nitrogen fixation relative to the wet lowland occupied by P. mariana and L. laricina. Average nitrogen-fixing capacity (by acetylene reduction) was greater among bacteria isolates from L. laricina than those from P. mariana. Azospirillum spp. were strongly associated with P. mariana, while Azotobacter spp. were isolated more frequently from L. laricina.

scholarly journals Nitrogen Fixation in Pozol, a Traditional Fermented Beverage

2020 ◽  
Vol 86 (16) ◽  
Author(s):  
Jocelin Rizo ◽  
Marco A. Rogel ◽  
Daniel Guillén ◽  
Carmen Wacher ◽  
Esperanza Martinez-Romero ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Growth Promotion ◽  
Point Of View ◽  
Intestinal Microbiome ◽  
Acetylene Reduction Activity ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Free Living ◽  
Functional Perspective

ABSTRACT Traditional fermentations have been widely studied from the microbiological point of view, but little is known from the functional perspective. In this work, nitrogen fixation by free-living nitrogen-fixing bacteria was conclusively demonstrated in pozol, a traditional Mayan beverage prepared with nixtamalized and fermented maize dough. Three aspects of nitrogen fixation were investigated to ensure that fixation actually happens in the dough: (i) the detection of acetylene reduction activity directly in the substrate, (ii) the presence of potential diazotrophs, and (iii) an in situ increase in acetylene reduction by inoculation with one of the microorganisms isolated from the dough. Three genera were identified by sequencing the 16S rRNA and nifH genes as Kosakonia, Klebsiella, and Enterobacter, and their ability to fix nitrogen was confirmed. IMPORTANCE Nitrogen-fixing bacteria are found in different niches, as symbionts in plants, in the intestinal microbiome of several insects, and as free-living microorganisms. Their use in agriculture for plant growth promotion via biological nitrogen fixation has been extensively reported. This work demonstrates the ecological and functional importance that these bacteria can have in food fermentations, reevaluating the presence of these genera as an element that enriches the nutritional value of the dough.

scholarly journals NITROGEN FIXING BACTERIA OF SPRING WHEAT ROOT ZONE

2013 ◽  
Vol 17 ◽  
pp. 7-20
Author(s):  
O. V. Nadkernychna ◽  
E. P. Kopylov
Keyword(s):  
Nitrogen Fixation ◽  
Spring Wheat ◽  
Root Zone ◽  
Molecular Nitrogen ◽  
Wheat Root ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Active Nitrogen ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity

The paper presents the study of active nitrogen fixation bacteria of genera Azotobacter, Azospirillum, Bacillus, Flavobacterium, Enterobacter and Pseudomonas isolated from root zone of spring wheat plants. The ability of selected diazotrophs to form associative systems with spring wheat was investigated. The most significant increase of molecular nitrogen fixation activity in root zone of plants was observed under the Azospirillum species background.

scholarly journals Nitrogen Fixing Bacteria and Their Application for Heavy Metal Removal: A Mini Review

2021 ◽  
Vol 9 (2) ◽  
pp. 43-47
Author(s):  
I. Lawal
Keyword(s):  
Heavy Metal ◽  
Nitrogen Fixation ◽  
Metal Removal ◽  
Heavy Metal Removal ◽  
Plant Diseases ◽  
Nitrogen Fixing ◽  
Cell Wall Degrading Enzymes ◽  
Nitrogen Fixing Bacteria ◽  
Symbiotic Associations ◽  
Terrestrial Environments

Nitrogen is a critical component of biological systems and typically serves as a constraint on production in both aquatic and terrestrial environments, although its shortage has been compensated for through the process of biological nitrogen fixation. Nitrogen fixation is a critical microbial activity that utilises nitrogenase enzymes to convert dinitrogen (N2) gas to ammonia (NH3). It is carried out by a diverse spectrum of bacteria known as nitrogen fixing bacteria. These include free-living bacteria such as Azotobacter, Bacillus, Beijerickia, and Clostridium, associative bacteria such as Azospirillum, Enterobacter, and Pseudomonas, and bacteria that form symbiotic associations with legumes such as Rhizobium and actinorrhizal plants such as Frankia. These bacteria contribute significantly to plant growth by producing phytohormones (such as auxins, cytokinins, gibberelins, and indole acetic acid), reducing the incidence of plant diseases through the production of siderophores and cell wall degrading enzymes, and increasing phosphorus nutrition via phosphate solubilization. Additionally, they remove heavy metal ions from solutions through a process called biosorption, which is a feasible, natural, environmentally benign, and economically viable technique of remediating heavy metal-contaminated environments.

scholarly journals Nitrogen Fixation and Translocation in Young Sugarcane (Saccharum officinarum L.) Plants Associated with Endophytic Nitrogen-Fixing Bacteria

2009 ◽  
Vol 24 (3) ◽  
pp. 224-230 ◽  
Author(s):  
Atsushi Momose ◽  
Norikuni Ohtake ◽  
Kuni Sueyoshi ◽  
Takashi Sato ◽  
Yasuhiro Nakanishi ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Saccharum Officinarum ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria
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