-
Applied Microbiology and Biotechnology Feb 2020Biological nitrogen fixation (BNF) is accomplished through the action of the oxygen-sensitive enzyme nitrogenase. One unique caveat of this reaction is the inclusion of... (Review)
Review
Biological nitrogen fixation (BNF) is accomplished through the action of the oxygen-sensitive enzyme nitrogenase. One unique caveat of this reaction is the inclusion of hydrogen gas (H) evolution as a requirement of the reaction mechanism. In the absence of nitrogen gas as a substrate, nitrogenase will reduce available protons to become a directional ATP-dependent hydrogenase. Aerobic nitrogen-fixing microbes are of particular interest, because these organisms have evolved to perform these reactions with oxygen-sensitive enzymes in an environment surrounded by oxygen. The ability to maintain a functioning nitrogenase in aerobic conditions facilitates the application of these organisms under conditions where most anaerobic nitrogen fixers are excluded. In recent years, questions related to the potential yields of the nitrogenase-derived products ammonium and H have grown more approachable to experimentation based on efforts to construct increasingly more complicated strains of aerobic nitrogen fixers such as the obligate aerobe Azotobacter vinelandii. This mini-review provides perspectives of recent and historical efforts to understand and quantify the yields of ammonium and H that can be obtained through the model aerobe A. vinelandii, and outstanding questions that remain to be answered to fully realize the potential of nitrogenase in these applications with model aerobic bacteria.
Topics: Aerobiosis; Ammonia; Azotobacter vinelandii; Hydrogen; Industrial Microbiology; Nitrogen-Fixing Bacteria; Nitrogenase
PubMed: 31879824
DOI: 10.1007/s00253-019-10210-9 -
PeerJ 2023The raising trend of cultivation of ()-transgenic cotton is faced with a new challenge what effects on the growth and yield of cotton under elevated CO.
BACKGROUND
The raising trend of cultivation of ()-transgenic cotton is faced with a new challenge what effects on the growth and yield of cotton under elevated CO.
METHODS
Rhizobacteria is the significant biological regulator to increase environmental suitability and ameliorate soil-nitrogen utilization efficiency of crops, especially cotton. Pot-culture experiments investigated the effects on the yield and fiber quality components of cotton (transgenic Line SCRC 37) inoculated with (AC) under elevated CO.
RESULTS
The findings indicated that the inoculation of azotobacter significantly improved the yield and fiber quality components of cotton, the elevated CO significantly increased the soil density of and the partial yield indexes (as cottonweightper 20 bolls, lint yield per 20 bolls and boll number per plant), and non-significant decrease the fiber quality components of cotton except uniform.
DISCUSSION
Overall results obviously depicted that the inoculation of azotobacter and the elevated CO had positive effects on the yield and fiber quality components of cotton. Presumably, azotobacter inoculation can be used to stimulate plant soil-nitrogen uptake and promote plant growth for cotton under elevated CO in the future.
Topics: Bacillus thuringiensis; Carbon Dioxide; Azotobacter; Soil; Gossypium; Nitrogen
PubMed: 37576495
DOI: 10.7717/peerj.15811 -
Biotechnology For Biofuels 2017Recently, issues concerning the sustainable and harmless disposal of organic solid waste have generated interest in microbial biotechnologies aimed at converting waste... (Review)
Review
Recently, issues concerning the sustainable and harmless disposal of organic solid waste have generated interest in microbial biotechnologies aimed at converting waste materials into bioenergy and biomaterials, thus contributing to a reduction in economic dependence on fossil fuels. To valorize biomass, waste materials derived from agriculture, food processing factories, and municipal organic waste can be used to produce biopolymers, such as biohydrogen and biogas, through different microbial processes. In fact, different bacterial strains can synthesize biopolymers to convert waste materials into valuable intracellular (e.g., polyhydroxyalkanoates) and extracellular (e.g., exopolysaccharides) bioproducts, which are useful for biochemical production. In particular, large numbers of bacteria, including , , , , , methylotrophs, spp., spp., spp., spp., and recombinant , have been successfully used to produce polyhydroxyalkanoates on an industrial scale from different types of organic by-products. Therefore, the development of high-performance microbial strains and the use of by-products and waste as substrates could reasonably make the production costs of biodegradable polymers comparable to those required by petrochemical-derived plastics and promote their use. Many studies have reported use of the same organic substrates as alternative energy sources to produce biogas and biohydrogen through anaerobic digestion as well as dark and photofermentation processes under anaerobic conditions. Therefore, concurrently obtaining bioenergy and biopolymers at a reasonable cost through an integrated system is becoming feasible using by-products and waste as organic carbon sources. An overview of the suitable substrates and microbial strains used in low-cost polyhydroxyalkanoates for biohydrogen and biogas production is given. The possibility of creating a unique integrated system is discussed because it represents a new approach for simultaneously producing energy and biopolymers for the plastic industry using by-products and waste as organic carbon sources.
PubMed: 28469708
DOI: 10.1186/s13068-017-0802-4 -
Chemosphere Feb 2023Soil salinization seriously affects crop yield and soil productivity. The application of bacteria and microalgae has been considered as a promising strategy to alleviate...
Improved effects of combined application of nitrogen-fixing bacteria Azotobacter beijerinckii and microalgae Chlorella pyrenoidosa on wheat growth and saline-alkali soil quality.
Soil salinization seriously affects crop yield and soil productivity. The application of bacteria and microalgae has been considered as a promising strategy to alleviate soil salinization. However, the effect of bacteria-microalgae symbiosis on saline-alkali land is still unclear. This study evaluated the effects of Azotobacter beijerinckii, Chlorella pyrenoidosa, and their combined application on the wheat growth and saline-alkali soil improvement. The results showed that, among all the treatments, A. beijerinckii + live C. pyrenoidosa combined inoculation group (BA) had the best effect on increasing wheat plant biomass, improving salt tolerance, and improving soil fertility. The dry weight of wheat plant in the BA group increased by 66.7%, 17.4%, and 35.0%, respectively, compared with the control group (CK), A. beijerinckii inoculation group (B), and live C. pyrenoidosa inoculation group (A). The total nitrogen content of wheat plant in the BA group increased by 69.5%, 76.7%, and 71.1%, compared with the CK, B, and A group. The proline content of wheat plant in the BA group was 100% higher than that in the CK group. The N/P ratio and K/Na ratio of wheat plant increased by 157% and 12.9% in the BA group compared with the CK group, respectively, which was more conducive to alleviating nitrogen limitation and salt stress. The A. beijerinckii + live C. pyrenoidosa inoculation treatment better reduced soil pH and improved the availability of phosphorus in soil. This study illustrated the comprehensive application prospects of bacteria-microalgae interactions on wheat growth promotion and soil improvement in saline-alkali land, and provided a new effective strategy for improving saline-alkali soil quality and increasing crop productivity.
Topics: Soil; Triticum; Alkalies; Chlorella; Microalgae; Nitrogen-Fixing Bacteria; Bacteria; Nitrogen
PubMed: 36457265
DOI: 10.1016/j.chemosphere.2022.137409 -
Current Protocols Jan 2022
PubMed: 35034426
DOI: 10.1002/cpz1.363 -
The Journal of Chemical Physics Jan 2017A new numerical scheme for RNA (ribonucleic acid) titration based on the Debye-Hückel framework for the salt description is proposed in an effort to reduce the...
A new numerical scheme for RNA (ribonucleic acid) titration based on the Debye-Hückel framework for the salt description is proposed in an effort to reduce the computational costs for further applications to study protein-RNA systems. By means of different sets of Monte Carlo simulations, we demonstrated that this new scheme is able to correctly reproduce the experimental titration behavior and salt pK shifts. In comparison with other theoretical approaches, similar or even better outcomes are achieved at much lower computational costs. The model was tested on the lead-dependent ribozyme, the branch-point helix, and the domain 5 from Azotobacter vinelandii Intron 5.
Topics: Azotobacter vinelandii; Introns; Models, Chemical; Molecular Dynamics Simulation; Monte Carlo Method; Protein Structure, Secondary; Protons; RNA; RNA, Catalytic; Titrimetry
PubMed: 28109220
DOI: 10.1063/1.4972986 -
Microorganisms Sep 2022Drought stress is one of the most severe abiotic stresses affecting soil fertility and plant health, and due to climate change, it is destined to increase even further,...
Drought stress is one of the most severe abiotic stresses affecting soil fertility and plant health, and due to climate change, it is destined to increase even further, becoming a serious threat to crop production. An efficient, eco-friendly alternative is the use of plant growth-promoting bacteria (PGPB), which can promote plant fitness through direct and indirect approaches, protecting plants from biotic and abiotic stresses. The present study aims to identify bacterial consortia to promote L. cv Matador's seed germination and protect its seedlings from drought stress. Eight PGPB strains belonging to , and genera, previously characterized in physiological conditions, were analyzed under water-shortage conditions, and a germination bioassay was carried out by biopriming seeds with either individual strains or consortia. The consortia of RHF6, LMG9814, and . AGS84 displayed the capacity to positively affect seed germination and seedlings' radical development in both standard and drought conditions, ameliorating the plants' growth rate compared to the untreated ones. These results sustain using PGPB consortia as a valid ameliorating water stress strategy in the agro-industrial field.
PubMed: 36144400
DOI: 10.3390/microorganisms10091798 -
MBio Jun 2022Engineering plants to synthesize nitrogenase and assimilate atmospheric N will reduce crop dependency on industrial N fertilizers. This technology can be achieved by...
Engineering plants to synthesize nitrogenase and assimilate atmospheric N will reduce crop dependency on industrial N fertilizers. This technology can be achieved by expressing prokaryotic nitrogen fixation gene products for the assembly of a functional nitrogenase in plants. NifB is a critical nitrogenase component since it catalyzes the first committed step in the biosynthesis of all types of nitrogenase active-site cofactors. Here, we used a library of 30 distinct sequences originating from different phyla and ecological niches to restore diazotrophic growth of an Azotobacter vinelandii mutant. Twenty of these variants rescued the mutant phenotype despite their phylogenetic distance to A. vinelandii. Because multiple protein interactions are required in the iron-molybdenum cofactor (FeMo-co) biosynthetic pathway, the maturation of nitrogenase in a heterologous host can be divided in independent modules containing interacting proteins that function together to produce a specific intermediate. Therefore, functional modules composed of a variant, together with the A. vinelandii NifS and NifU proteins (for biosynthesis of NifB [FeS] clusters) and the FdxN ferredoxin (for NifB function), were expressed in Nicotiana benthamiana chloroplasts and mitochondria. Three archaeal NifB proteins accumulated at high levels in soluble fractions of chloroplasts (Methanosarcina acetivorans and Methanocaldococcus infernus) or mitochondria ( and Methanothermobacter thermautotrophicus). These NifB proteins were shown to accept [FeS] clusters from NifU and were functional in FeMo-co synthesis . The accumulation of significant levels of soluble and functional NifB proteins in chloroplasts and mitochondria is critical to engineering biological nitrogen fixation in plants. Biological nitrogen fixation is the conversion of inert atmospheric dinitrogen gas into nitrogen-reactive ammonia, a reaction catalyzed by the nitrogenase enzyme of diazotrophic bacteria and archaea. Because plants cannot fix their own nitrogen, introducing functional nitrogenase in cereals and other crop plants would reduce our strong dependency on N fertilizers. NifB is required for the biosynthesis of the active site cofactors of all nitrogenases, which arguably makes it the most important protein in global nitrogen fixation. NifB functionality is therefore a requisite to engineer a plant nitrogenase. The expression of genes from a wide range of prokaryotes into the model diazotroph Azotobacter vinelandii shows a surprising level of genetic complementation suggestive of plasticity in the nitrogenase biosynthetic pathway. In addition, we obtained NifB proteins from both mitochondria and chloroplasts of tobacco that are functional after reconstitution by providing [FeS] clusters from NifU, paving the way to nitrogenase cofactor biosynthesis in plants.
Topics: Archaeal Proteins; Azotobacter vinelandii; Bacterial Proteins; Chloroplasts; Fertilizers; Iron Compounds; Mitochondria; Nitrogen; Nitrogen Fixation; Nitrogenase; Phylogeny; Nicotiana
PubMed: 35695456
DOI: 10.1128/mbio.00268-22 -
International Journal of Molecular... Dec 2022The enzymatic transformation of various chemicals, especially using NADPH-dependent hydroxylase, into more soluble and/or high value-added products has steadily garnered...
The enzymatic transformation of various chemicals, especially using NADPH-dependent hydroxylase, into more soluble and/or high value-added products has steadily garnered increasing attention. However, the industrial application of these NADPH-dependent hydroxylases has been limited due to the high cost of the cofactor NADPH. As an alternative, enzymatic NADPH-regeneration systems have been developed and are frequently used in various fields. Here, we expressed and compared two recombinant isocitrate dehydrogenases (IDHs) from and in . Both enzymes were hyper-expressed in the soluble fraction of and were single-step purified to apparent homogeneity with yields of more than 850 mg/L. These enzymes also functioned well when paired with NADPH consumption systems. Specifically, NADPH was regenerated from NADP when an NADPH-consuming cytochrome P450 BM3 from was incorporated. Therefore, both enzymes could be used as alternatives to the commonly used regeneration system for NADPH. These enzymes also have promising potential as genetic fusion partners with NADPH-dependent enzymes due to the monomeric nature of their quaternary structure, thereby resulting in self-sufficient biocatalysts via NADPH regeneration in a single polypeptide with NADPH-dependent activity.
Topics: Azotobacter vinelandii; NADP; Isocitrate Dehydrogenase; Corynebacterium glutamicum; Escherichia coli; Cytochrome P-450 Enzyme System
PubMed: 36499645
DOI: 10.3390/ijms232315318 -
Microbiological Research Sep 2021This group has previously reported the role of ascorbic acid (AA) as an antioxidant for survivability and ability to enhancing diazotrophic efficacy in Azotobacter...
Combined application of ascorbic acid and endophytic N-fixing Azotobacter chroococcum Avi2 modulates photosynthetic efficacy, antioxidants and growth-promotion in rice under moisture deficit stress.
This group has previously reported the role of ascorbic acid (AA) as an antioxidant for survivability and ability to enhancing diazotrophic efficacy in Azotobacter chroococcum Avi2 under hydrogen peroxide (HO) stress. However, the present study showed the combined application of AA and Avi2 in drought-susceptible (IR64 and Naveen) and drought-tolerant (Ankit and Satyabhama) rice cultivars to determine their photosynthetic efficacy (chlorophyll fluorescence-imaging), antioxidants, and plant growth-promotion (PGP) under moisture deficit stress (MS, -60 kPa). The results indicated that combined application of AA and Avi2 significantly (p < 0.05) increased the total chlorophyll, relative water content, electrolytic leakage, super oxide dismutase, and catalase activities in all rice cultivars as compared to other MS treatments, whereas stress indicators like proline and HO contents were proportionally increased under MS and their concentration were normalized under combined application of AA and Avi2. Photochemical quenching, non-photochemical quenching, photosynthetic electron transport rate, and the effective quantum efficiency were found to be increased significantly (p < 0.05) in Avi2 + AA as compared to other MS treatments. Moreover, rice roots harbored significantly (p < 0.05) higher copy number of nifH gene in Avi2 + AA treatment followed by Avi2 compared to flooded control and other MS treatments. Combined application of AA and Avi2 also increased the grain yield significantly (p < 0.05) by 7.09 % and 3.92 % in drought-tolerant (Ankit and Satyabhama, respectively) and 31.70 % and 34.19 % in drought-susceptible (IR64 and Naveen, respectively) rice cultivars compared to MS treatment. Overall, the present study indicated that AA along with Avi2 could be an effective formulation to alleviate MS vis à vis enhances PGP traits in rice.
Topics: Antioxidants; Ascorbic Acid; Azotobacter; Chlorophyll; Endophytes; Nitrogen Fixation; Oryza; Oxidation-Reduction; Photosynthesis; Plant Leaves; Plant Roots; Stress, Physiological; Water
PubMed: 34146939
DOI: 10.1016/j.micres.2021.126808