Novel Approach for the Determination of Nitrogen Fixation in Cyanobacteria

2019 ◽  
Vol 41 (1) ◽  
pp. 105-105
Author(s):  
Sumaira Mazhar Sumaira Mazhar ◽  
Jerry D Cohen and Shahida Hasnain Jerry D Cohen and Shahida Hasnain
Keyword(s):  
Nitrogen Fixation ◽  
Growth Conditions ◽  
Nitrogen Enrichment ◽  
Nitrogen Fixing ◽  
Cultivation Conditions ◽  
Novel Approach ◽  
Detailed Method ◽  
Study Support ◽  
Novel Approaches

Non-heterocystous nitrogen fixing strains of cyanobacteria were screened by their ability to grow in nitrogen deficient media. The selected nitrogen fixing cyanobacterial cells were then cultured in BG11 media supplemented with [15N]-labeled sodium nitrate. Under these growth conditions any organic [14N] found in the cyanobacterial cells would simply come from nitrogen fixation because [15N] was the only available source of nitrogen in the medium. Amino acids extracted after different time periods (after 15, 30, 40, 50 and 60 days of inoculation) were used for the determination of the 14N/15N ratio using GC-MS. Results from the present study support the conclusion that at stationary phase of growth cyanobacterial nitrogen fixation was no longer supplying a significant amount of nitrogen. This approach not only provided a detailed method for the evaluation of the nitrogen fixing potential of the cyanobacteria in culture, but also suggests novel approaches for the assessment of the ability of the strains to provide nitrogen enrichment to plants under co-cultivation conditions.

scholarly journals Characterisation of a Novel Nitrogen-Fixing, Polyhydroxyalkanoate-Producing Bacterium, Novosphingobium Nitrogenifigens Y88T

2021 ◽  
Author(s):  
◽  
Anne-Marie Smit
Keyword(s):  
Nitrogen Fixation ◽  
Model Organism ◽  
Dry Weight ◽  
Growth Conditions ◽  
Biofuel Production ◽  
Nitrogen Fixing ◽  
Production Environment ◽  
Amino Terminal ◽  
Nitrogen Utilisation ◽  
Pha Production

<p>The novel sphingomonad Novosphingobium nitrogenifigens Y88T (Y88T) is an obligate aerobe able to grow in nutrient-imbalanced environments where nitrogen is naturally limiting, but carbon is found in abundance. Due to its ability to fix atmospheric nitrogen and produce the bioplastic polyhydroxyalkanoate (PHA), Y88T is well-suited for growth in a nitrogenlimited but carbon-enriched environment. Because of these metabolic abilities, Y88T is of interest as a model organism for PHA production unconstrained by nitrogen-limiting conditions. Growth profiles and PHA production profiles were determined for Y88T under conditions of carbon enrichment, nitrogen sufficiency and depletion to investigate carbon and nitrogen utilisation as well as PHA production in this organism. Also, since the nitrogenase enzyme required for nitrogen fixation is oxygen labile, the effect of DO concentration and the relationship between aerobic metabolism and the nitrogen-fixing and PHA-producing abilities of Y88T was investigated. This study demonstrated: that glucose is the preferred growth substrate for Y88T; that no direct relationship exists between nitrogen fixation and PHB accumulation in Y88T; that Y88T can reliably produce in excess of 80 % of its dry weight as polyhydroxybutyrate (PHB), a type of PHA, from glucose under nitrogenlimiting conditions. Proteomic signatures were determined for the various physiological responses of Y88T to growth, nitrogen utilisation, PHB production and exposure to different levels of DO. More than 250 unique proteins, including the core nitrogen-fixation, PHB-synthetic and glycolytic proteins were identified. Y88T apparently converts glucose to PHB via three interrelated glucose catabolic pathways and proteins likely involved in these pathways were identified. This study revealed that, regardless of growth conditions and despite decreased abundance of the Y88T nitrogenase enzyme, growth and PHB synthesis were not inhibited at DOhigh concentrations. Proteomic characterisation of the Y88T phasin, a PHA granule-associated protein, iii identified an amino-terminal, low complexity alanine and proline rich segment found only in other sphingomonads. The expression level of the Y88T phasin correlated well with PHB yields, suggesting the use of this protein as a biomarker to optimise PHB yield in a production environment. Y88T has the potential to be a useful production strain in pure culture, utilising its natural and robust propensity to metabolise glucose to preferentially produce PHB. Targets for biotechnological improvement and the potential for application of Y88T to biofuel production are discussed.</p>

scholarly journals Characterisation of a Novel Nitrogen-Fixing, Polyhydroxyalkanoate-Producing Bacterium, Novosphingobium Nitrogenifigens Y88T

2021 ◽  
Author(s):  
◽  
Anne-Marie Smit
Keyword(s):  
Nitrogen Fixation ◽  
Model Organism ◽  
Dry Weight ◽  
Growth Conditions ◽  
Biofuel Production ◽  
Nitrogen Fixing ◽  
Production Environment ◽  
Amino Terminal ◽  
Nitrogen Utilisation ◽  
Pha Production

<p>The novel sphingomonad Novosphingobium nitrogenifigens Y88T (Y88T) is an obligate aerobe able to grow in nutrient-imbalanced environments where nitrogen is naturally limiting, but carbon is found in abundance. Due to its ability to fix atmospheric nitrogen and produce the bioplastic polyhydroxyalkanoate (PHA), Y88T is well-suited for growth in a nitrogenlimited but carbon-enriched environment. Because of these metabolic abilities, Y88T is of interest as a model organism for PHA production unconstrained by nitrogen-limiting conditions. Growth profiles and PHA production profiles were determined for Y88T under conditions of carbon enrichment, nitrogen sufficiency and depletion to investigate carbon and nitrogen utilisation as well as PHA production in this organism. Also, since the nitrogenase enzyme required for nitrogen fixation is oxygen labile, the effect of DO concentration and the relationship between aerobic metabolism and the nitrogen-fixing and PHA-producing abilities of Y88T was investigated. This study demonstrated: that glucose is the preferred growth substrate for Y88T; that no direct relationship exists between nitrogen fixation and PHB accumulation in Y88T; that Y88T can reliably produce in excess of 80 % of its dry weight as polyhydroxybutyrate (PHB), a type of PHA, from glucose under nitrogenlimiting conditions. Proteomic signatures were determined for the various physiological responses of Y88T to growth, nitrogen utilisation, PHB production and exposure to different levels of DO. More than 250 unique proteins, including the core nitrogen-fixation, PHB-synthetic and glycolytic proteins were identified. Y88T apparently converts glucose to PHB via three interrelated glucose catabolic pathways and proteins likely involved in these pathways were identified. This study revealed that, regardless of growth conditions and despite decreased abundance of the Y88T nitrogenase enzyme, growth and PHB synthesis were not inhibited at DOhigh concentrations. Proteomic characterisation of the Y88T phasin, a PHA granule-associated protein, iii identified an amino-terminal, low complexity alanine and proline rich segment found only in other sphingomonads. The expression level of the Y88T phasin correlated well with PHB yields, suggesting the use of this protein as a biomarker to optimise PHB yield in a production environment. Y88T has the potential to be a useful production strain in pure culture, utilising its natural and robust propensity to metabolise glucose to preferentially produce PHB. Targets for biotechnological improvement and the potential for application of Y88T to biofuel production are discussed.</p>

Does Dryas integrifolia fix nitrogen?

Botany ◽  
2009 ◽  
Vol 87 (11) ◽  
pp. 1106-1109 ◽  
Author(s):  
John H. Markham
Keyword(s):  
Nitrogen Fixation ◽  
Strong Evidence ◽  
Host Plants ◽  
Symbiotic Nitrogen Fixation ◽  
Growth Conditions ◽  
Nitrogen Fixing ◽  
Purshia Tridentata ◽  
Alnus Viridis ◽  
Vegetatively Propagated Plants ◽  
Different Sources

Symbiotic nitrogen fixation is found in plant taxa that also include non-nitrogen-fixing members. Strong evidence for the occurrence of nitrogen fixation comes from physiological measurements and the identification of the nitrogen fixing symbiont. This evidence has been provided for Dryas drummondii Richardson ex Hook. in the Rosaceae. However, while there have been numerous references to the nitrogen fixing ability of Dryas integrifolia Vahl., they can all be traced to a single report that did not provide strong evidence for nitrogen fixation. My attempts to establish nitrogen fixing nodules on vegetatively propagated plants from the field, or seedlings of D. integrifolia, using three different sources of Frankia , all failed. Since other host plants ( Alnus viridis (Chaix) DC. subsp. crispa (Aiton) Turrill and Purshia tridentata (Pursh.) DC.) did produce nitrogen-fixing nodules under the same growth conditions, the ability of D. integrifolia to fix nitrogen should be considered suspect.

The Use of TMAH to Etch Silicon and Expose Metal Bridging Failures

2000 ◽  
Author(s):  
Mark Morris ◽  
James Mohr ◽  
Esteban Ortiz ◽  
Steven Englebretson
Keyword(s):  
Failure Mechanism ◽  
Schottky Diodes ◽  
Tetramethylammonium Hydroxide ◽  
Novel Approach ◽  
Failure Location ◽  
Metal Etching ◽  
Plastic Mold

Abstract Determination of metal bridging failures on plastic encapsulated devices is difficult due to the metal etching effects that occur while removing many of the plastic mold compounds. Typically, the acids used to remove the encapsulation are corrosive to the metals that are found within the device. Thus, decapsulation can result in removal of the failure mechanism. Mechanical techniques are often not successful due to damage that results in destruction of the die and failure mechanism. This paper discusses a novel approach to these types of failures using a silicon etch and a backside evaluation. The desirable characteristics of the technique would be to remove the silicon and leave typical device metals unaffected. It would also be preferable that the device passivation and oxides not be etched so that the failure location is not disturbed. The use of Tetramethylammonium Hydroxide (TMAH), was found to fit these prerequisites. The technique was tested on clip attached Schottky diodes that exhibited resistive shorting. The use of the TMAH technique was successful at exposing thin solder bridges that extruded over the edge of the die resulting in failure.

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.

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.

scholarly journals Characterization of the Antibiotic Compound No. 70 Produced byStreptomycessp. IMV-70

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Lyudmila P. Trenozhnikova ◽  
Almagul K. Khasenova ◽  
Assya S. Balgimbaeva ◽  
Galina B. Fedorova ◽  
Genrikh S. Katrukha ◽  
...  
Keyword(s):  
Optimal Growth ◽  
Growth Conditions ◽  
Culture Broth ◽  
Producer Strain ◽  
New Class ◽  
New Antibiotics ◽  
Actinomycete Strain ◽  
Main Component

We describe the actinomycete strain IMV-70 isolated from the soils of Kazakhstan, which produces potent antibiotics with high levels of antibacterial activity. After the research of its morphological, chemotaxonomic, and cultural characteristics, the strain with potential to be developed further as a novel class of antibiotics with chemotherapeutics potential was identified asStreptomycessp. IMV-70. In the process of fermentation, the strainStreptomycesspp. IMV-70 produces the antibiotic no. 70, which was isolated from the culture broth by extraction with organic solvents. Antibiotic compound no. 70 was purified and separated into individual components by HPLC, TLC, and column chromatography methods. The main component of the compound is the antibiotic 70-A, which was found to be identical to the peptolide etamycin A. Two other antibiotics 70-B and 70-C have never been described and therefore are new antibiotics. The physical-chemical and biological characteristics of these preparations were described and further researched. Determination of the optimal growth conditions to cultivate actinomycete-producer strain IMV-70 and development of methods to isolate, purify, and accumulate preparations of the new antibiotic no. 70 enable us to research further the potential of this new class of antibiotics.

Carbon Nanotubes Grown on Metallic Wires by Cold Plasma Technique

2002 ◽  
Vol 737 ◽  
Author(s):  
D. Sarangi ◽  
A. Karimi
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Growth Conditions ◽  
Effect Of Temperature ◽  
Rutherford Back Scattering ◽  
Novel Approach ◽  
Transmission Electron ◽  
Back Scattering ◽  
Metallic Wires ◽  
Metal Wires

ABSTRACTCarbon nanotubes on metallic wires may be act as electrode for the field emission (FE) luminescent devices. Growing nanotubes on metallic wires with controlled density, length and alignment are challenging issues for this kind of devices. We, in the present investigation grow carbon nanotubes directly on the metal wires by a powerful but simple technique. A novel approach has been proposed to align nanotubes during growth. Methane, acetylene and dimethylamine have been used as source gases. With the same growth conditions (viz. pressure, growth temperature and plasma) methane does not produce any nanotube but nanotubes grown with dimethylamine show shorter length and radius than acetylene. The effect of temperature to control the radius, time to control the density, plasma conditions to align the nanotubes has been focused. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Rutherford Back Scattering (RBS) are used to characterize the nanotubes.

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