scholarly journals Adverse effects of nitrogenous compounds on nitrogen-fixing cyanobacterium Anabaena solitaria Klebahn

2020 ◽  
Vol 49 (4) ◽  
pp. 1095-1101
Author(s):  
Nermin Adel El Semary
Keyword(s):  
Nitrogen Fixation ◽  
Heterotrophic Bacteria ◽  
Nitrogen Sources ◽  
The Other ◽  
Nitrogen Compounds ◽  
Nitrogen Fixing ◽  
Nitrogenous Compounds ◽  
Heterocystous Cyanobacterium ◽  
Massive Growth ◽  
Cyanobacterium Anabaena

The nitrogen-fixing heterocystous cyanobacterium Anabaena solitaria was tested for its response to different concentrations of nitrogen sources, namely nitrate and ammonia. To compare both the effect of concentration and type of nitrogen source, gradual concentrations were prepared for both ammonia and nitrate. The results showed concentration was significantly important on the frequency of heterocyst formation where highest nitrogen compounds concentrations were inhibitory for heterocyst formation. On the other hand, the effect of the type of nitrogenous compounds tested was insignificant which only proves that they are equally usable by cyanobacteria which will use them instead of transforming one of its cells to heterocyst thus not performing nitrogen fixation. Results also revealed the massive growth of heterotrophic bacteria in presence of nitrogenous compounds. This indicates that the presence of nitrogenous compounds in fields in which nitrogen-fixing cyanobacteria are to be used as biofertilizers can be inhibitory for nitrogen fixation and stimulatory for heterotrophic bacterial growth which could be pathogenic and harmful to plants. The use of more nitrogen-fixing cyanobacteria with the minimum amount of nitrogenous compounds is recommended.

Regulation of nitrogen-fixation by different nitrogen sources in the marine non-heterocystous cyanobacterium Trichodesmium sp. NIBB1067

1991 ◽  
Vol 156 (5) ◽  
pp. 335-337 ◽  
Author(s):  
Kaori Ohki ◽  
Jonathan P. Zehr ◽  
Paul G. Falkowski ◽  
Yoshihiko Fujita
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Sources ◽  
Heterocystous Cyanobacterium

Investigations on the root nodule bacteria of leguminous plants: XIX. Influence of various factors on the excretion of nitrogenous compounds from the nodules

1937 ◽  
Vol 27 (3) ◽  
pp. 332-348 ◽  
Author(s):  
Artturi Ilmari Virtanen ◽  
Synnöve von Hausen ◽  
Tauno Laine
Keyword(s):  
Amino Acids ◽  
Nitrogen Fixation ◽  
Root Nodule ◽  
Nitrogen Nutrition ◽  
Nitrogen Compounds ◽  
Nodule Bacteria ◽  
Fixed Nitrogen ◽  
Nitrogenous Compounds ◽  
Primary Products ◽  
Equal Effectiveness

1. It has been shown experimentally that the excretion of nitrogen noted by us in cultures of inoculated legumes takes place from the nodule bacteria, probably from the intranodular ones, and not from the roots. No excretion of amino acids occurs in cultures of uninoculated legumes growing on nitrate nitrogen.2. Our earlier hypothesis that the legumes receive their nitrogen nutrition from the nodules in the form of organic nitrogen compounds, particularly amino acids, is in perfect accord with our new observations concerning the process of excretion. All facts indicate that the amino acids concerned are primary products of the nitrogen fixation, and not breakdown products of proteins. Bond's valuable work along quite different lines produced results which support this conclusion. He, however, did not study the chemical nature of the nitrogen compounds in question.3. The excretion of nitrogen occurs in media capable of absorbing the excreted nitrogen compounds (cellulose, kaolin, sand, soil). The demonstration of the excretion is not possible in water cultures except when very large quantities of water are used. On the basis of these facts a hypothesis is advanced to explain the nature of the excretion.4. The term total fixed nitrogen has been used as an expression for the extent of nitrogen fixation, while the term extent of excretion is employed to indicate that percentage of the total fixed nitrogen which is excreted from the nodules.5. The extent of excretion depends largely on the strain used for inoculation. With strains of apparently equal effectiveness in nitrogen fixation, the extent of excretion may vary considerably, so that actually such strains differ in their effectiveness.

scholarly journals Distribution and Abundance of Azotobacter in Wheat Fields of Bangladesh

1970 ◽  
Vol 24 (2) ◽  
pp. 151-153
Author(s):  
Muhammad Ali Akond ◽  
Sanzida Mubassara ◽  
M Motiur Rahman
Keyword(s):  
Nitrogen Fixation ◽  
Laboratory Condition ◽  
Rhizosphere Soil ◽  
Heterotrophic Bacteria ◽  
Soil Samples ◽  
Nitrogen Fixing ◽  
Positive Correlation ◽  
Wheat Field

The distribution and abundance of Azotobacter as well as heterotrophic bacteria in root, rhizosphere soil and non-rhizosphere soil samples from various wheat fields of four different areas under three districts were investigated in this study. The potential for nitrogen-fixation of five Azotobacter isolates was also detected. All samples tested were positive in their capacity to harbouring Azotobacter with a range of 26-100%. The population of heterotrophic bacteria ranged from 2.1 x 107 to 1.2 x 108 cfu/g sample. Ranges of total number of Azotobacter in different samples were 5.2 x 104 to 7.2 x 104 cfu/g, 17.2 x 104 to 25.5 x 104 cfu/g, and 12.4 x 104 to 16.7 x 104 cfu/g respectively for root, rhizosphere soil and non-rhizosphere soil. A positive correlation was found in Azotobacter colonization between root and rhizosphere, but it was negative in case of the population between heterotrophic bacteria and Azotobacter in rhizosphere. The highest amount of N was found to be fixed by the isolate M1 and the lowest by the isolate M4 and it was respectively 9.26 and 5.45 mg N/g substrate. In terms of the capacity to fix nitrogen in laboratory condition the five isolates of Azotobacter could be arranged as M1> M3 > M5 > M4 > M2. Keywords: Azotobacter, Wheat field, Nitrogen fixing potentialDOI: http://dx.doi.org/10.3329/bjm.v24i2.1262

MOLECULAR HYDROGEN AND NITROGEN FIXATION BY CLOSTRIDIUM PASTEURIANUM

1959 ◽  
Vol 5 (6) ◽  
pp. 617-620 ◽  
Author(s):  
D. W. S. Westlake ◽  
P. W. Wilson
Keyword(s):  
Nitrogen Fixation ◽  
Molecular Hydrogen ◽  
Competitive Inhibitor ◽  
The Other ◽  
Clostridium Pasteurianum ◽  
Shake Culture ◽  
Nitrogen Fixing ◽  
Cultural Conditions ◽  
A Value ◽  
Hydrogen Inhibition

The total amount of nitrogen fixed and the efficiency of nitrogen fixation, by strain Clostridium pasieurianum W5 have been increased by using improved cultural conditions. Also, consistent growth of the organism in shake culture has been obtained. Evidence is presented supporting the view that hydrogen is a specific, competitive inhibitor of nitrogen fixation in this organism. The Km for nitrogen fixation is around 0.03 atmosphere and the estimated Ki for hydrogen inhibition is 0.5 ± 0.05 atmosphere, a value considerably higher than that found in the other nitrogen-fixing systems studied.

scholarly journals Overexpression of the groESL Operon Enhances the Heat and Salinity Stress Tolerance of the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC7120

2009 ◽  
Vol 75 (18) ◽  
pp. 6008-6012 ◽  
Author(s):  
Akhilesh Kumar Chaurasia ◽  
Shree Kumar Apte
Keyword(s):  
Nitrogen Fixation ◽  
Stress Tolerance ◽  
Salinity Stress ◽  
Expression Vector ◽  
Nitrogen Fixing ◽  
Ambient Conditions ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Salinity Stress Tolerance

ABSTRACT The bicistronic groESL operon, encoding the Hsp60 and Hsp10 chaperonins, was cloned into an integrative expression vector, pFPN, and incorporated at an innocuous site in the Anabaena sp. strain PCC7120 genome. In the recombinant Anabaena strain, the additional groESL operon was expressed from a strong cyanobacterial P psbA1 promoter without hampering the stress-responsive expression of the native groESL operon. The net expression of the two groESL operons promoted better growth, supported the vital activities of nitrogen fixation and photosynthesis at ambient conditions, and enhanced the tolerance of the recombinant Anabaena strain to heat and salinity stresses.

scholarly journals NtrC, The Master Regulator Controls the Utilization of Alternative Nitrogen Sources in Pseudomonas Stutzeri A1501

2021 ◽  
Author(s):  
Zhimin Yang ◽  
Qin Li ◽  
Yongliang Yan ◽  
Xiubin Ke ◽  
Yueyue Han ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Nitrogen Fixation ◽  
Nitrogen Metabolism ◽  
Nitrate Assimilation ◽  
Pseudomonas Stutzeri ◽  
Nitrogen Sources ◽  
Phenotypic Analysis ◽  
Nitrogenous Compounds ◽  
And Oxidative Stress

Abstract Pseudomonas stutzeri A1501 is the model strain for studying associative nitrogen fixation and possesses the nitrogen regulatory NtrC protein in the core genome. Nitrogen source is one of the important factors affecting the efficiency of biological nitrogen fixation in the natural environment. However, the regulation of NtrC in nitrogen metabolism of P. stutzeri A1501 is not clear. In this work, phenotypic analysis of the ntrC mutant characterized the roles of NtrC for the nitrogen metabolism and oxidative stress response of P. stutzeri A1501. To systematically identify NtrC-controlled gene expression, RNA-seq was performed to further analyze the gene expression differences between the wild type strain and the ∆ntrC mutant under nitrogen fixation conditions. A total of 1431 genes were found to be significantly altered by the ntrC deletion, among which 147 associative genes had NtrC-binding sites, and pathways for nitrogen fixation regulation, the acquisition and catabolism of nitrogenous compounds and nitrate assimilation were particularly discussed. Furthermore, the oxidative stress-related gene (katB), upregulated by the ntrC deletion, was suggested to be the potential target gene of NtrC, underlining the importance of NtrC to nitrogenase protection against oxygen damage. Based on these findings, we propose that NtrC is a high-ranked element in the regulatory network of P. stutzeri A1501 that controls a variety of nitrogen metabolic and oxidative stress responsive traits required for adaptation to complex rhizosphere environment.

scholarly journals Plasmids Related to the Symbiotic Nitrogen Fixation Are Not Only Cooperated Functionally but Also May Have Evolved over a Time Span in Family Rhizobiaceae

2020 ◽  
Vol 12 (11) ◽  
pp. 2002-2014
Author(s):  
Ling-Ling Yang ◽  
Zhao Jiang ◽  
Yan Li ◽  
En-Tao Wang ◽  
Xiao-Yang Zhi
Keyword(s):  
Nitrogen Fixation ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Symbiotic Nitrogen Fixation ◽  
Gene Families ◽  
Time Span ◽  
Soil Conditions ◽  
Gene Gain ◽  
Nitrogen Fixing ◽  
Pan Genome

Abstract Rhizobia are soil bacteria capable of forming symbiotic nitrogen-fixing nodules associated with leguminous plants. In fast-growing legume-nodulating rhizobia, such as the species in the family Rhizobiaceae, the symbiotic plasmid is the main genetic basis for nitrogen-fixing symbiosis, and is susceptible to horizontal gene transfer. To further understand the symbioses evolution in Rhizobiaceae, we analyzed the pan-genome of this family based on 92 genomes of type/reference strains and reconstructed its phylogeny using a phylogenomics approach. Intriguingly, although the genetic expansion that occurred in chromosomal regions was the main reason for the high proportion of low-frequency flexible gene families in the pan-genome, gene gain events associated with accessory plasmids introduced more genes into the genomes of nitrogen-fixing species. For symbiotic plasmids, although horizontal gene transfer frequently occurred, transfer may be impeded by, such as, the host’s physical isolation and soil conditions, even among phylogenetically close species. During coevolution with leguminous hosts, the plasmid system, including accessory and symbiotic plasmids, may have evolved over a time span, and provided rhizobial species with the ability to adapt to various environmental conditions and helped them achieve nitrogen fixation. These findings provide new insights into the phylogeny of Rhizobiaceae and advance our understanding of the evolution of symbiotic nitrogen fixation.

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