scholarly journals Synthesis of Nitrogenase by Paenibacillus Sabinae T27 in Presence of High Levels of Ammonia During Anaerobic Fermentation

2020 ◽  
Author(s):  
Qin Li ◽  
Xiao-Juan He ◽  
Peng-Xi Liu ◽  
Hao-Wei Zhang ◽  
Ming-Yang Wang ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Anaerobic Fermentation ◽  
High Energy ◽  
Liquid Chromatography Mass Spectrometry ◽  
High Concentration ◽  
Qrt Pcr ◽  
Mofe Protein ◽  
Fe Protein ◽  
Nitrogenase Activities ◽  
Nitrogen Excess

Abstract BackgroundBiological nitrogen fixation catalyzed by nitrogenase is a high energy-intensive process, and thus nitrogenase synthesis and activity are inhibited by ammonium (NH4+). Microorganism fix nitrogen at high ammonium (30-300 mM) concentration has not been reported before.ResultsPaenibacillus sabinae T27, a Gram-positive, spore-forming diazotroph (N2-fixing microorganism, showed nitrogenase activities not only in low (0-4 mM) concentration of NH4+, but also in high (30-300 mM) concentration of NH4+, no matter whether the cells of this bacterium were grown in flask or in fermentor on scale cultivation. qRT-PCR and western blotting analysis supported that Fe protein and MoFe protein were synthesized under both low (0-4 mM) and high (30-300 mM) concentration of NH4+. Liquid chromatography-mass spectrometry（LC-MS）analysis revealed that MoFe protein purified form cultures grown in nitrogen-limited condition or nitrogen-excess condition was encoded by nifDK and Fe protein was encoded by both nifH and nifH2. The cross-reaction suggested the purified Fe and MoFe components from P. sabinae T27 grown in both nitrogen-limited and -excess conditions were active.ConclusionsOur results indicate that N2 fixation occurs in presence of high (30-300 mM) concentration of NH4+ in P. sabinae T27. Nitrogen fixation under both low and high concentration of NH4+ was catalyzed by the same nitrogenases and the Fe protein was encoded by both nifH and nifH2. Our study will provide a clue for studying the mechanisms on nitrogen fixation in presence of the high concentration of NH4+.

Biological nitrogen fixation: fundamentals

1982 ◽  
Vol 296 (1082) ◽  
pp. 375-385 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Biological Nitrogen Fixation ◽  
Mofe Protein ◽  
Fe Protein ◽  
Metal Contents ◽  
Physiological Constraint ◽  
Biological Nitrogen

The enzyme responsible for N 2 fixation, nitrogenase, is only found in prokaryotes. It consists of two metalloproteins, both irreversibly destroyed by exposure to the O 2 of air. The MoFe-protein binds N 2 and the Fe-protein, after activation by MgATP, supplies electrons. H 2 is evolved during the reduction of N 2 to NH 3 and can become the sole reaction in the absence of N 2 ; valuable information has been obtained by exploiting the ability of nitrogenase to reduce substrates such as acetylene, azides and cyanides. Substrate quantities of MgATP are required for all such reactions. The sensitivity of nitrogenase to oxygen is an important physiological constraint on its use and distribution; the ATP requirement and metal contents are less serious constraints. O 2 and NH 3 regulate synthesis and sometimes function of nitrogenase. Nitrogen fixation by Klebsiella pneumoniae is genetically encoded by 17 genes (the nif genes) in a cluster of seven or eight operons. The functions of several of these genes are known and the outlines of their regulation can be discerned. The nif cluster can be transferred to new prokaryotic genera, sometimes yielding new diazotrophic strains or species; they have been transferred to yeast and are silent. They have been cloned and alien DNA ( lac ) has been fused into nif Transfer of expressible nif to new genetic backgrounds has probably occurred in Nature and may be exploitable for agriculture.

scholarly journals Paenibacillus strains with nitrogen fixation and multiple beneficial properties for promoting plant growth

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7445 ◽  
Author(s):  
Xiaomeng Liu ◽  
Qin Li ◽  
Yongbin Li ◽  
Guohua Guan ◽  
Sanfeng Chen
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Plant Pathogens ◽  
Dry Weight ◽  
Gibberella Zeae ◽  
Bacterial Strains ◽  
Gene Encoding ◽  
Fe Protein ◽  
Large Genus ◽  
Nitrogenase Activities

Paenibacillus is a large genus of Gram-positive, facultative anaerobic, endospore-forming bacteria. The genus Paenibacillus currently comprises more than 150 named species, approximately 20 of which have nitrogen-fixation ability. The N2-fixing Paenibacillus strains have potential uses as a bacterial fertilizer in agriculture. In this study, 179 bacterial strains were isolated by using nitrogen-free medium after heating at 85 °C for 10 min from 69 soil samples collected from different plant rhizospheres in different areas. Of the 179 bacterial strains, 25 Paenibacillus strains had nifH gene encoding Fe protein of nitrogenase and showed nitrogenase activities. Of the 25 N2-fixing Paenibacillus strains, 22 strains produced indole-3-acetic acid (IAA). 21 strains out of the 25 N2-fixing Paenibacillus strains inhibited at least one of the 6 plant pathogens Rhizoctonia cerealis, Fusarium graminearum, Gibberella zeae, Fusarium solani, Colletotrichum gossypii and Alternaria longipes. 18 strains inhibited 5 plant pathogens and Paenibacillus sp. SZ-13b could inhibit the growth of all of the 6 plant pathogens. According to the nitrogenase activities, antibacterial capacities and IAA production, we chose eight strains to inoculate wheat, cucumber and tomato. Our results showed that the 5 strains Paenibacillus sp. JS-4, Paenibacillus sp. SZ-10, Paenibacillus sp. SZ-14, Paenibacillus sp. BJ-4 and Paenibacillus sp. SZ-15 significantly promoted plant growth and enhanced the dry weight of plants. Hence, the five strains have the greater potential to be used as good candidates for biofertilizer to facilitate sustainable development of agriculture.

scholarly journals The Quorum Sensing Auto-Inducer 2 (AI-2) Stimulates Nitrogen Fixation and Favors Ethanol Production over Biomass Accumulation in Zymomonas mobilis

2021 ◽  
Vol 22 (11) ◽  
pp. 5628
Author(s):  
Valquíria Campos Alencar ◽  
Juliana de Fátima dos Santos Silva ◽  
Renata Ozelami Vilas Boas ◽  
Vinícius Manganaro Farnézio ◽  
Yara N. L. F. de Maria ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Quorum Sensing ◽  
Ethanol Production ◽  
N2 Fixation ◽  
Energy Demand ◽  
Zymomonas Mobilis ◽  
Biomass Accumulation ◽  
High Energy ◽  
Gram Negative ◽  
Expression Of Genes

Autoinducer 2 (or AI-2) is one of the molecules used by bacteria to trigger the Quorum Sensing (QS) response, which activates expression of genes involved in a series of alternative mechanisms, when cells reach high population densities (including bioluminescence, motility, biofilm formation, stress resistance, and production of public goods, or pathogenicity factors, among others). Contrary to most autoinducers, AI-2 can induce QS responses in both Gram-negative and Gram-positive bacteria, and has been suggested to constitute a trans-specific system of bacterial communication, capable of affecting even bacteria that cannot produce this autoinducer. In this work, we demonstrate that the ethanologenic Gram-negative bacterium Zymomonas mobilis (a non-AI-2 producer) responds to exogenous AI-2 by modulating expression of genes involved in mechanisms typically associated with QS in other bacteria, such as motility, DNA repair, and nitrogen fixation. Interestingly, the metabolism of AI-2-induced Z. mobilis cells seems to favor ethanol production over biomass accumulation, probably as an adaptation to the high-energy demand of N2 fixation. This opens the possibility of employing AI-2 during the industrial production of second-generation ethanol, as a way to boost N2 fixation by these bacteria, which could reduce costs associated with the use of nitrogen-based fertilizers, without compromising ethanol production in industrial plants.

scholarly journals Advanced Nonflammable Localized High‐Concentration Electrolyte for High Energy Density Lithium Battery

2021 ◽  
Author(s):  
Mengmin Jia ◽  
Chi Zhang ◽  
Yawei Guo ◽  
Linshan Peng ◽  
Xiaoyan Zhang ◽  
...  
Keyword(s):  
Energy Density ◽  
Lithium Battery ◽  
High Energy ◽  
High Energy Density ◽  
High Concentration

Electron transfer and half-reactivity in nitrogenase

2011 ◽  
Vol 39 (1) ◽  
pp. 201-206 ◽  
Author(s):  
Thomas A. Clarke ◽  
Shirley Fairhurst ◽  
David J. Lowe ◽  
Nicholas J. Watmough ◽  
Robert R. Eady
Keyword(s):  
Electron Transfer ◽  
Protein Molecule ◽  
Stopped Flow ◽  
Protein Binding Sites ◽  
Molybdenum Iron Protein ◽  
Iron Protein ◽  
Mofe Protein ◽  
Fe Protein ◽  
Rapid Quench ◽  
Important Enzyme

Nitrogenase is a globally important enzyme that catalyses the reduction of atmospheric dinitrogen into ammonia and is thus an important part of the nitrogen cycle. The nitrogenase enzyme is composed of a catalytic molybdenum–iron protein (MoFe protein) and a protein containing an [Fe4–S4] cluster (Fe protein) that functions as a dedicated ATP-dependent reductase. The current understanding of electron transfer between these two proteins is based on stopped-flow spectrophotometry, which has allowed the rates of complex formation and electron transfer to be accurately determined. Surprisingly, a total of four Fe protein molecules are required to saturate one MoFe protein molecule, despite there being only two well-characterized Fe-protein-binding sites. This has led to the conclusion that the purified Fe protein is only half-active with respect to electron transfer to the MoFe protein. Studies on the electron transfer between both proteins using rapid-quench EPR confirmed that, during pre-steady-state electron transfer, the Fe protein only becomes half-oxidized. However, stopped-flow spectrophotometry on MoFe protein that had only one active site occupied was saturated by approximately three Fe protein equivalents. These results imply that the Fe protein has a second interaction during the initial stages of mixing that is not involved in electron transfer.

scholarly journals Potential of Phototrophic Purple Nonsulfur Bacteria to Fix Nitrogen in Rice Fields

2021 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Isamu Maeda
Keyword(s):  
Nitrogen Fixation ◽  
Regulatory Networks ◽  
Nitrogenase Activity ◽  
Field Studies ◽  
Rice Fields ◽  
Purple Nonsulfur Bacteria ◽  
Available Nitrogen ◽  
Nitrogenase Activities ◽  
Plant Available Nitrogen ◽  
Biological Nitrogen

Biological nitrogen fixation catalyzed by Mo-nitrogenase of symbiotic diazotrophs has attracted interest because its potential to supply plant-available nitrogen offers an alternative way of using chemical fertilizers for sustainable agriculture. Phototrophic purple nonsulfur bacteria (PNSB) diazotrophically grow under light anaerobic conditions and can be isolated from photic and microaerobic zones of rice fields. Therefore, PNSB as asymbiotic diazotrophs contribute to nitrogen fixation in rice fields. An attempt to measure nitrogen in the oxidized surface layer of paddy soil estimates that approximately 6–8 kg N/ha/year might be accumulated by phototrophic microorganisms. Species of PNSB possess one of or both alternative nitrogenases, V-nitrogenase and Fe-nitrogenase, which are found in asymbiotic diazotrophs, in addition to Mo-nitrogenase. The regulatory networks control nitrogenase activity in response to ammonium, molecular oxygen, and light irradiation. Laboratory and field studies have revealed effectiveness of PNSB inoculation to rice cultures on increases of nitrogen gain, plant growth, and/or grain yield. In this review, properties of the nitrogenase isozymes and regulation of nitrogenase activities in PNSB are described, and research challenges and potential of PNSB inoculation to rice cultures are discussed from a viewpoint of their applications as nitrogen biofertilizer.

scholarly journals Porous Aromatic Melamine Schiff Bases as Highly Efficient Media for Carbon Dioxide Storage

Processes ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 17 ◽  
Author(s):  
Raghad M. Omer ◽  
Emaad T. B. Al-Tikrity ◽  
Gamal A. El-Hiti ◽  
Mohammed F. Alotibi ◽  
Dina S. Ahmed ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Schiff Bases ◽  
Energy Demand ◽  
Gas Adsorption ◽  
Co2 Storage ◽  
High Energy ◽  
Co2 Production ◽  
Co2 Uptake ◽  
High Concentration ◽  
Average Pore

High energy demand has led to excessive fuel consumption and high-concentration CO2 production. CO2 release causes serious environmental problems such as the rise in the Earth’s temperature, leading to global warming. Thus, chemical industries are under severe pressure to provide a solution to the problems associated with fuel consumption and to reduce CO2 emission at the source. To this effect, herein, four highly porous aromatic Schiff bases derived from melamine were investigated as potential media for CO2 capture. Since these Schiff bases are highly aromatic, porous, and have a high content of heteroatoms (nitrogen and oxygen), they can serve as CO2 storage media. The surface morphology of the Schiff bases was investigated through field emission scanning electron microscopy, and their physical properties were determined by gas adsorption experiments. The Schiff bases had a pore volume of 0.005–0.036 cm3/g, an average pore diameter of 1.69–3.363 nm, and a small Brunauer–Emmett–Teller surface area (5.2–11.6 m2/g). The Schiff bases showed remarkable CO2 uptake (up to 2.33 mmol/g; 10.0 wt%) at 323 K and 40 bars. The Schiff base containing the 4-nitrophenyl substituent was the most efficient medium for CO2 adsorption and, therefore, can be used as a gas sorbent.

scholarly journals High-Energy Solid Fuel Obtained from Carbonized Rice Starch

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4096
Author(s):  
Beata Kurc ◽  
Piotr Lijewski ◽  
Łukasz Rymaniak ◽  
Paweł Fuć ◽  
Marita Pigłowska ◽  
...  
Keyword(s):  
Solid Fuel ◽  
Calorific Value ◽  
High Energy ◽  
Nitrogen Atmosphere ◽  
Rice Starch ◽  
Hard Coal ◽  
High Concentration ◽  
Combustion Heat ◽  
Technical Parameters ◽  
Very High

The paper describes the investigations of the physicochemical properties of biocoal, a solid fuel obtained following the carbonization of rice starch. The production of biocoal (carbonization) was completed at the temperature of 600 °C in the nitrogen atmosphere. As a result of the carbonization, amorphous carbon with high monodispersity was obtained, devoided of oxygen elements and was a very well developed BET specific surface—360 m2 g−1. The investigations of the technical parameters have confirmed a very high concentration of energy. The calorific value of 53.21 MJ kg−1 and the combustion heat of 54.92 MJ kg−1 are significantly higher than those of starch before carbonization (18.72 MJ kg−1 and 19.43 MJ kg−1, respectively) and these values for typical biomass fuels. These values are also greater than those of hard coal. Other advantageous features of the obtained fuel are low ash (0.84%) and moisture content. These features predispose this fuel for the application as an alternative to conventional fuels.

Study of Gas Production by Anaerobic Fermentation and Microbial Community Changes by In-Situ Microaerobic Desulphurization

2020 ◽  
Vol 14 (4) ◽  
pp. 517-523
Author(s):  
Yan Zhou ◽  
Hucheng Liu ◽  
Wei Kou ◽  
Lijie Shao ◽  
Peihan Liu ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
High Efficiency ◽  
Anaerobic Fermentation ◽  
Low Cost ◽  
Total Solid ◽  
Common Species ◽  
Gas Production ◽  
High Concentration ◽  
Fermentation System ◽  
The Stability

The enhancement of biogas quality at low cost and high efficiency process was one of the purposes of biogas engineering. In this work, we designed a reactor for microaerobic desulphurization. We used this reactor to study the anaerobic fermentation in systems that used cow manure with total solid (TS) concentrations of 18.5%, 15% and 10%. The influence of anaerobic fermentation on the stability of gas production and the characteristics of the gas produced with different concentrations of fermentation materials was studied. The strain structure of the fermentation system was obtained by high-throughput sequencing and taxonomy was compared. The H2S removal results showed that the average rates of the H2S removal in concentrations of fermentation materials of 18.5%, 15%, and 10% TS were 99.2%, 97.8%, and 78.8%, respectively. 16SrRNA sequencing was performed in different fermented samples as well as a comparison between samples in order to determine the number of unique species (NUS) and the number of common species (NCS). By comparing TS 18.5 with TS 15 and TS 10 samples, it was determined that under fermentation conditions, NUS were 113 and 106, respectively. Whereas NUS were 31 and 41, respectively, when comparing TS 15 and TS 10. These demonstrated that the number of strain species in the fermentation system with TS 18.5% was far more than those found in the systems with low concentration of fermentation. Also, the ability for disturbance resistance of the microaerobic desulphurization system was stronger at high concentration of the fermentation.

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