Cloning and characterization of nifA and ntrC genes of the stem nodulating bacterium ORS571, the nitrogen fixing symbiont of Sesbania rostrata: Regulation of nitrogen fixation (nif) genes in the free living versus symbiotic state

1987 ◽  
Vol 206 (2) ◽  
pp. 207-219 ◽  
Author(s):  
K. Pawlowski ◽  
P. Ratet ◽  
J. Schell ◽  
F. J. de Bruijn
Keyword(s):  
Nitrogen Fixation ◽  
Sesbania Rostrata ◽  
Nif Genes ◽  
Nitrogen Fixing ◽  
Free Living

NON-SYMBIOTIC NITROGEN FIXATION IN SOME QUEBEC SOILS

1965 ◽  
Vol 11 (1) ◽  
pp. 29-38 ◽  
Author(s):  
P-C. Chang ◽  
R. Knowles
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Soil Types ◽  
Anaerobic Incubation ◽  
Nitrogen Fixing ◽  
Free Living ◽  
Aerobic Conditions ◽  
Bacterial Counts ◽  
Facultatively Anaerobic ◽  
Nitrogen Fixers

The occurrence of free-living nitrogen fixers, the potential for nitrogen fixation, and the correlation between the nitrogen-fixing capacities of the soils and bacterial counts were studied using representative Quebec soils.Clostridium occurred more frequently than did Azotobacter. Studies with N15showed that nitrogen fixation was more frequent under anaerobic than under aerobic conditions in all the soil types studied in their unamended state. The addition of glucose stimulated nitrogen fixation. During anaerobic incubation, nitrogen fixation was found to be correlated significantly with the increase in numbers of both total aerobes and Clostridia. The results suggested that facultatively anaerobic nitrogen fixers, and aerobic nitrogen fixers other than Azotobacter, were present.

Genetics of plant-microbe nitrogen-fixing symbiosis

1985 ◽  
Vol 85 (3-4) ◽  
pp. 239-252
Author(s):  
G. C. Machray ◽  
W. D. P. Stewart
Keyword(s):  
Nitrogen Fixation ◽  
Genetic Analysis ◽  
Symbiotic Nitrogen Fixation ◽  
Model System ◽  
Present Knowledge ◽  
Nitrogen Fixing ◽  
Free Living ◽  
Genetic Level ◽  
And Control ◽  
Control Of Expression

SynopsisA wide variety of plant-microbe nitrogen-fixing symbioses which include cyanobacteria as the nitrogenfixing partner exist. While some information has been gathered on the biochemical changes in the cyanobacterium upon entering into symbiosis, very little is known about the accompanying changes at the genetic level. Much of our present knowledge of the organisation and control of expression of nitrogenfixation (nif) genes is derived from studies of the free-living diazotroph Klebsiella pneumoniae. This organism thus provides a model system and source of experimental material for the genetic analysis of symbiotic nitrogen fixation. We describe the use of cloned K. pneumoniae genes for nitrogen fixation and its regulation in the genetic analysis' of nitrogen fixation in cyanobacteria which can enter into symbiosis with plants. These studies reveal some dissimilarities in the organisation of nif genes and raise questions as to the genetic control of nitrogen fixation in symbiosis.

Characterization of a nitrogen-fixing bacterial strain from the roots of Digitaria sanguinalis

1976 ◽  
Vol 22 (2) ◽  
pp. 254-260 ◽  
Author(s):  
Lynn E. Barber ◽  
Harold J. Evans
Keyword(s):  
Nitrogen Fixation ◽  
Bacterial Strain ◽  
Optimal Growth ◽  
Root Systems ◽  
Mixed Cultures ◽  
Nitrogen Fixing ◽  
Digitaria Sanguinalis ◽  
Gram Negative ◽  
Root Sample

Rates of nitrogen fixation of 3 to 10 g of N2 fixed per hectare per day were associated with root systems of Digitaria sanguinalis. A Gram-negative motile aerobic bacterial strain that was capable of N2 fixation was isolated from a washed root sample of one of these plants. Optimal growth and N2 fixation occurred at a pH of about 6.5, a temperature of 30–37 °C, and at a pO2 of about 0.01 atm. Increased rates of N2 fixation resulted when this strain was grown in mixed cultures with aerobic or facultative bacteria. Observations of cellular and cultural morphology and results of biochemical and physiological studies indicate that the isolate may be related to the Azotobacteraceae but that it is not identical with any of the members of this family. The importance of N2 fixation by this isolate in nature is unknown.

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.

Dynamics of free-living nitrogen-fixing bacterial populations and nitrogen fixation in a two-prey–one-predator system

2008 ◽  
Vol 218 (3-4) ◽  
pp. 323-338 ◽  
Author(s):  
A. Kavadia ◽  
D.V. Vayenas ◽  
S. Pavlou ◽  
G. Aggelis
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Fixing ◽  
Free Living ◽  
Bacterial Populations ◽  
Predator System

Cloning and characterization of the nifA gene from Herbaspirillum seropedicae strain Z78

1991 ◽  
Vol 37 (6) ◽  
pp. 425-429 ◽  
Author(s):  
Emanuel M. Souza ◽  
Shigehiro Funayama ◽  
Liu U. Rigo ◽  
Fábio O. Pedrosa
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Genomic Library ◽  
Acetylene Reduction Activity ◽  
Nif Genes ◽  
Herbaspirillum Seropedicae ◽  
Reduction Activity ◽  
Nitrogen Fixation Gene ◽  
Nifa Gene

A genomic library of Herbaspirillum seropedicae was constructed and screened for the nifA gene by complementation of a nifA mutant of Azospirillum brasilense (FP10). A recombinant plasmid, pEMS1, capable of restoring acetylene reduction activity in the mutant FP10, was isolated and found to hybridize to the nifA gene of Klebsiella pneumoniae. The results suggest that nifA is involved in the regulation of nif genes in H. seropedicae. Key words: diazotroph, nitrogen fixation gene, nif regulation, complementation cloning, Herbaspirillum seropedicae.

scholarly journals DNA Methylation in Ensifer Species during Free-Living Growth and during Nitrogen-Fixing Symbiosis with Medicago spp.

mSystems ◽  
2022 ◽  
Author(s):  
George C. diCenzo ◽  
Lisa Cangioli ◽  
Quentin Nicoud ◽  
Janis H. T. Cheng ◽  
Matthew J. Blow ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Methylation ◽  
Nitrogen Fixation ◽  
Terminal Differentiation ◽  
Nitrogen Fixing ◽  
Bacterial Transformation ◽  
Free Living

Nitrogen fixation by rhizobia in symbiosis with legumes is economically and ecologically important. The symbiosis can involve a complex bacterial transformation—terminal differentiation—that includes major shifts in the transcriptome and cell cycle.

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