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1.
Sci Rep ; 12(1): 15837, 2022 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-36151202

RESUMO

Licorice (Glycyrrhiza glabra L.) is an industrial medicinal plant that is potentially threatened by extinction. In this study, the effects of salinity (0 and 200 mM sodium chloride (NaCl)) and Azotobacter inoculation were evaluated on 16 licorice accessions. The results showed that salinity significantly reduced the fresh and dry biomass (FW and DW, respectively) of roots, compared to plants of the control group (a decrease of 15.92% and 17.26%, respectively). As a result of bacterial inoculation, the total sugar content of roots increased by 21.56% when salinity was applied, but increased by 14.01% without salinity. Salinity stress increased the content of glycyrrhizic acid (GA), phenols, and flavonoids in licorice roots by 104.6%, 117.2%, and 56.3%, respectively. Integrated bacterial inoculation and salt stress significantly increased the GA content in the accessions. Bajgah and Sepidan accessions had the highest GA contents (96.26 and 83.17 mg/g DW, respectively), while Eghlid accession had the lowest (41.98 mg/g DW). With the bacterial application, the maximum amounts of glabridin were obtained in Kashmar and Kermanshah accessions (2.04 and 1.98 mg/g DW, respectively). Bajgah and Kashmar accessions had higher amounts of rutin in their aerial parts (6.11 and 9.48 mg/g DW, respectively) when their roots were uninoculated. In conclusion, these results can assist in selecting promising licorice accessions for cultivation in harsh environments.


Assuntos
Azotobacter , Glycyrrhiza , Triterpenos , Flavonoides/metabolismo , Glycyrrhiza/metabolismo , Ácido Glicirrízico , Irã (Geográfico) , Fenóis/metabolismo , Extratos Vegetais/metabolismo , Raízes de Plantas/metabolismo , Rutina , Salinidade , Estresse Salino , Cloreto de Sódio/metabolismo , Açúcares/metabolismo , Triterpenos/metabolismo
2.
BMC Plant Biol ; 22(1): 322, 2022 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-35790900

RESUMO

BACKGROUND: Glycyrrhiza glabra L. is a medicinal and industrial plant that has gone extinct due to different abiotic stress caused by climate change. To understand how the plant-associated microorganism can support this plant under salinity, we collected sixteen Iranian accessions of G. glabra L., inoculated their rhizomes with Azotobacter sp. (two levels, bacterial treatments, and no-bacterial treatments, and grown them under salinity stress (NaCl levels; 0, and 200 mM). RESULTS: Two accessions of Bardsir and Bajgah significantly showed higher resistant to salinity, for example by increasing crown diameter (11.05 and 11 cm, respectively) compared to an average diameter of 9.5 in other accessions. Azotobacter inoculation caused a significant increase in plant height and crown diameter. Among studied accessions, Kashmar (46.21%) and Ilam (44.95%) had the highest rate of membrane stability index (MSI). Evaluation of enzyme activity represented that bacterial application under salinity, increased polyphenol oxidase (PPO) (0.21 U mg-1 protein), peroxidase (POD) (3.09 U mg-1 protein U mg-1 protein), and phenylalanine ammonia-lyase (PAL) (17.85 U mg-1 protein) activity. Darab accession showed the highest increase (6.45%) in antioxidant potential compared with all studied accessions under Azotobacter inoculation. According to principal component analysis (PCA), it was found that the accession of Meshkinshahr showed a more remarkable ability to activate its enzymatic defense system under salt stress. Also, three accessions of Meshkinshahr, Eghlid, and Ilam were categorized in separated clusters than other accessions regarding various studied treatments. CONCLUSION: Analysis indicated that five accessions of Meshkinshahr, Rabt, Piranshahr, Bardsir, and Kermanshah from the perspective of induced systematic resistance are the accessions that showed a greater morphophysiological and biochemical outcome under salinity. This study suggested that, inoculation of with Azotobacter on selected accession can relieve salt stress and support industrial mass production under abiotic condition.


Assuntos
Azotobacter , Glycyrrhiza , Estresse Salino , Triterpenos , Espécies em Perigo de Extinção , Glycyrrhiza/microbiologia , Glycyrrhiza/fisiologia , Irã (Geográfico)
3.
J Appl Microbiol ; 133(4): 2430-2444, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35809236

RESUMO

AIMS: In the study, seven Plant Growth Promoting Rhizobacteria (PGPR) Azotobacter species were screened against three strains of Fusarium verticillioides to test its antifungal activity. Azotobacter strains were tested for the degradation of fumonisin produced by F. verticillioides. Secondary metabolites were isolated and characterized from the Azotobacter strains for the first time. METHODS AND RESULTS: Potential seven Azotobacter species antifungal activity was tested following the dual culture assay against three strains of Fusarium verticillioides namely FVM-42, FVM-86 and MTCC156 estimating the substantial zone of inhibition. Azotobacter species AZT-31 and AZT-50 strains significantly inhibited the growth of F. verticillioides recording drastic growth enhancement of maize under in-vitro conditions by calculating the infection incidence, vigour index and germination percentage. As confirmation, dereplication studies were conducted for the reconfirmation of Azotobacter strains by isolating from rhizoplane. Azotobacter strains played a key role in the degradation of fumonisin produced by F. verticillioides reporting 98% degradation at 2 h of incubation with the pathogen. Furthermore, in the study first time, we have tried to isolate and characterize the secondary metabolites from the Azotobacter strains exhibiting six compounds from the species AZT-31 (2) and AZT-50 (4). Preliminary in-vitro experiments were carried out using the compounds extracted to check the reduction of infection incidence (90%) and increase in germination percentage upto 50 to 70% when compared to the test pathogen. CONCLUSION: Azotobacter strains referred as PGPR on influencing the growth of plant by producing certain substances that act as stimulators on inhibiting the growth of the pathogen. SIGNIFICANCE AND IMPACT OF THE STUDY: The future perspective would be the production of an active combination of carboxamide compound and Azotobacter species for preventively controlling the phytopathogenic fungi of plants and crops and also towards the treatment of seeds.


Assuntos
Azotobacter , Fumonisinas , Fusarium , Antifúngicos/farmacologia , Fumonisinas/metabolismo , Zea mays/microbiologia
4.
Microbiol Res ; 262: 127075, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35688099

RESUMO

In the present study Piriformospora indica (Pi) a phyto-promotional fungus and Azotobacter chroococcumWR5 (AzWR5) a rhizobacterium, were symbiotically evaluated for their role in improving the nutritional quality of wheat (Triticum aestivum L.). Co-inoculation of Pi+AzWR5 modified root system architecture of host and along with increasing the proportion of finer roots by 88% and 92% in C306 and Hd2967 respectively. Furthermore, the synergistic impact of Pi+AzWR5 interplayed for enhanced accumulation of Zn and Fe in different plant parts including grains (3.12 and 1.33 fold respectively). Pi+AzWR5 increased the transfer factor of Zn (62%, 94%, 91% and 213%) and Fe (31%, 54%, 68% and 32%) in root, stem, leaves and grains, respectively, and translocation factor of Zn (20%, 18% and 63%) and Fe (18%, 29% and 29%) for root-stem, root-leaves and root-grains, respectively. In addition to these co-inoculation of endophytes led to several fold increase in expression of four ZIP transporter genes in roots and shoot. In addition to these symbiotic association of endophytes with host led to 3 fold increase in grain yield. We thereby conclude that co-inoculation of Pi+AzWR5 substantially improves mobilization of Zn and Fe from soil and increase its concentration in grains as well as improves crop yield.


Assuntos
Azotobacter , Biofortificação , Azotobacter/genética , Azotobacter/metabolismo , Basidiomycota , Endófitos/genética , Endófitos/metabolismo , Ferro/metabolismo , Raízes de Plantas/metabolismo , Triticum/microbiologia , Zinco/metabolismo
5.
J Biotechnol ; 353: 51-60, 2022 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-35691257

RESUMO

Adhatoda vasica is used in the treatment of cold, cough, chronic bronchitis, asthma, diarrhea, and dysentery. The biological activities of this species are attributed with the presence of alkaloids, triterpenoids, and flavonoids. Agrobacterium rhizogenes-mediated transformation of A. vasica, produces pyrroloquinazoline alkaloids, was achieved by infecting leaf discs with strain ATCC15834. The bacterial strain infected 82.7% leaf discs and 5-7 hairy root initials were developed from the cut edges of leaf discs. In this study, seven strains of Azotobacter chroococcum and five strains of Pseudomonas putida were used for the biotization of hairy roots. Plant growth-promoting rhizobacteria (PGPR) develops symbiotic association with roots of plants and increases the growth parameters of plants. PGPR (A. chroococcum and P. putida) increased the profiles of nitrogenase and acid phosphatase enzymes, biomass, dry matter contents, anthranilate synthase activity and accumulation of pyrroloquizoline alkaloids in the biotized hairy roots. Both enzymes (nitrogenase and acid phosphatase) maintain sufficient supply of nitrogen and dissolved phosphorus to the cells of hairy roots therefore, the levels of anthranilate synthase activity and pyrroloquinazoline alkaloids are increased. Total seven pyrroloquinazoline alkaloids (vasicine, vasicinone, vasicine acetate, 2-acetyl benzyl amine, vasicinolone, deoxyvasicine and vasicol) were identified from the biotized hairy roots of A. vasica. In our study, biotization increased the profiles of pyrroloquinazoline alkaloids therefore, this strategy may be used in increasing the production of medicinally important secondary metabolites in other plant species also. Our hypothetical model demonstrates that P. putida cell surface receptors receive root exudates by attaching on hairy roots. After attachment, the bacterial strain penetrates in the biotized hairy roots. This endophytic interaction stimulates acid phosphatase activity in the cells of biotized hairy roots. The P. putida plasmid gene (ppp1) expression led to the synthesis of acid phosphatase in cytosol. The enzyme enhances phosphorus availability as well as induces the formation of phosphoribosyl diphosphate. Later, phosphoribosyl diphosphate metabolizes to tryptophan and finally tryptophan converts to anthranilic acid. The synthesized anthranilic acid used in the synthesis of alkaloids in A. vasica.


Assuntos
Alcaloides , Justicia, Planta , Pseudomonas putida , Fosfatase Ácida/metabolismo , Alcaloides/metabolismo , Alcaloides/farmacologia , Antranilato Sintase/genética , Antranilato Sintase/metabolismo , Azotobacter , Difosfatos/metabolismo , Nitrogenase/metabolismo , Fósforo/metabolismo , Raízes de Plantas/metabolismo , Pseudomonas putida/genética , Triptofano/metabolismo
6.
Biol Lett ; 18(3): 20210612, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35317624

RESUMO

Declining food production in African agroecosystems is attributable to changes in weather patterns, soil infertility and limited farming inputs. The exploitation of plant growth-promoting soil microbes could remedy these problems. Such microbes include Azotobacter; free-living, nitrogen-fixing bacteria, which confer stress tolerance, avail phytohormones and aid in soil bioremediation. Here, we aimed to isolate, characterize and determine the biodiversity of native Azotobacter isolates from soils in semi-arid Eastern Kenya. Isolation was conducted on nitrogen-free Ashby's agar and the morphological, biochemical and molecular attributes evaluated. The isolates were sequenced using DNA amplicons of 27F and 1492R primers of the 16S rRNA gene loci. The Basic Local Alignment Search Tool (BLASTn) analysis of their sequences revealed the presence of three main Azotobacter species viz., Azotobacter vinelandii, Azotobacter salinestris and Azotobacter tropicalis. Kitui County recorded the highest number of recovered Azotobacter isolates (45.4%) and lowest diversity index (0.8761). Tharaka Nithi County showed the lowest occurrence (26.36%) with a diversity index of (1.057). The diversity was influenced by the soil pH, texture and total organic content. This study reports for the first time a wide diversity of Azotobacter species from a semi-arid agroecosystem in Kenya with potential for utilization as low-cost, free-living nitrogen-fixing bioinoculant.


Assuntos
Azotobacter , Microbiologia do Solo , Azotobacter/genética , Quênia , Nitrogênio , RNA Ribossômico 16S/genética , Solo
7.
Sci Rep ; 12(1): 4182, 2022 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-35264690

RESUMO

Since nitrogenase is irreversibly inactivated within a few minutes after exposure to oxygen, current studies on the heterologous expression of nitrogenase are limited to anaerobic conditions. This study comprehensively identified genes showing oxygen-concentration-dependent expression only under nitrogen-fixing conditions in Azotobacter vinelandii, an aerobic diazotroph. Among the identified genes, nafU, with an unknown function, was greatly upregulated under aerobic nitrogen-fixing conditions. Through replacement and overexpressing experiments, we suggested that nafU is involved in the maintenance of nitrogenase activity under aerobic nitrogenase activity. Furthermore, heterologous expression of nafU in nitrogenase-producing Escherichia coli increased nitrogenase activity under aerobic conditions by 9.7 times. Further analysis of NafU protein strongly suggested its localization in the inner membrane and raised the possibility that this protein may lower the oxygen concentration inside the cells. These findings provide new insights into the mechanisms for maintaining stable nitrogenase activity under aerobic conditions in A. vinelandii and provide a platform to advance the use of nitrogenase under aerobic conditions.


Assuntos
Azotobacter vinelandii , Azotobacter , Azotobacter vinelandii/genética , Azotobacter vinelandii/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Nitrogênio/metabolismo , Fixação de Nitrogênio , Nitrogenase/genética , Nitrogenase/metabolismo , Oxigênio/metabolismo
8.
Chemosphere ; 294: 133702, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35066073

RESUMO

Graphene has found important applications in various areas and hundred tons of graphene materials are annually produced. It is crucial to investigate both the negative and positive environmental effects of graphene materials to ensure the safe applications and develop environmental applications. In this study, we reported the stimulating effects of reduced graphene oxide (RGO) to nitrogen-fixing bacterium Azotobacter chroococcum. RGO stimulated the cell growth of A. chroococcum at 0.010-0.500 mg/mL according to the growth curves and the colony-forming unit (CFU) increases. RGO wrapped over the A. chroococcum cells without inducing ultrastructural changes. RGO decreased the leakage of cell membrane, but slight oxidative stress was observed in A. chroococcum. RGO promoted the nitrogen fixation activity of A. chroococcum at 0.5 mg/mL according to both isotope dilution method and acetylene reduction activity measurements. Consequently, the increases of soil nitrogen contents were evidenced, in particular about 30% increase of organic nitrogen occurred at 0.5 mg/mL of RGO. In addition, RGO might possibly benefit the plant growth through enhancing the indoleacetic acid production of A. chroococcum. These results highlighted the positive environmental effects of graphene materials to nitrogen-fixing bacteria in nitrogen cycle.


Assuntos
Azotobacter , Grafite , Azotobacter/metabolismo , Grafite/metabolismo , Nitrogênio/metabolismo , Nitrogênio/farmacologia , Fixação de Nitrogênio
9.
Microbiol Res ; 250: 126808, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34146939

RESUMO

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 (H2O2) 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 H2O2 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.


Assuntos
Ácido Ascórbico/farmacologia , Azotobacter/fisiologia , Fixação de Nitrogênio , Oryza/efeitos dos fármacos , Oryza/microbiologia , Fotossíntese/efeitos dos fármacos , Água , Antioxidantes/farmacologia , Clorofila/análise , Clorofila/metabolismo , Endófitos/fisiologia , Oryza/genética , Oryza/crescimento & desenvolvimento , Oxirredução , Folhas de Planta/química , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Estresse Fisiológico/efeitos dos fármacos
10.
Food Funct ; 12(13): 5745-5754, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34018517

RESUMO

In this study, a glucanotransferase from prokaryotic Azotobacter chroococcum NCIMB 8003 was recombinantly expressed and its biochemical characteristics and bioconversion ability for starch were investigated. The purified enzyme has the optimum activity at 55 °C and pH 6.5-7.0, as well as a melting temperature of 62 °C. The double-charged ion Ca2+ stimulated the activity of the enzyme by approximately 2.4 times. The kinetic parameters and specificity analysis revealed that this glucanotransferase had a higher affinity for high-amylose starch. During the transglycosylation reaction, the starch molecule was converted into a relatively small polymer with a narrow size distribution. For the enzyme modification of high-amylose starch for 72 h, the amount of α-1,6 linkages increased from 1.9% to 22.7% and the content of resistant starch (RS) increased from 3.18% to 17.83%. In addition, the fine structure displayed the reuteran-like highly branched glucan linked by single linear α-1,6 linkages and α-1,4/6 branching points. These results revealed that a promising prebiotic dietary fiber was synthesized from starch with glucanotransferase modification.


Assuntos
Carboidratos da Dieta , Fibras na Dieta , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Amido/química , Amilose/química , Azotobacter , Glucanos , Peso Molecular , Prebióticos , Zea mays/química
11.
Appl Microbiol Biotechnol ; 105(11): 4487-4500, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34043079

RESUMO

Maize is an essential cereal crop and the third most essential food crop globally. The extensive dependence on pesticides and chemical fertilizers to control pests and increase crop yield, respectively, has generated an injurious impact on soil and animal health. Plant growth-promoting rhizobacteria (PGPR), which depict a broad array of bacteria inhabiting the root vicinity and root surface, have proven to be a better alternative. These organisms expressly or by implication foster the growth and development of plants by producing and secreting numerous regulatory compounds in the rhizosphere. Some rhizobacteria found to be in association with Zea mays rhizosphere include Bacillus sp., Azotobacter chroococcum, Burkholderia spp., Streptomyces spp., Pseudomonas spp., Paenibacillus spp., and Sphingobium spp. For this review, the mechanism of action of these rhizospheric bacteria was grouped into three, which are bioremediation, biofertilization, and biocontrol. KEY POINTS: • Plant-microbe interaction is vital for ecosystem functioning. • PGPR can produce volatile cues to deter ravaging insects from plants.


Assuntos
Ecossistema , Zea mays , Azotobacter , Bactérias , Raízes de Plantas , Rizosfera , Microbiologia do Solo
12.
Environ Sci Technol ; 55(8): 5301-5311, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33755424

RESUMO

In this study, the effects of in situ chemical oxidation (ISCO) on the biogeochemical properties of an aquifer soil were evaluated. Microcosms packed with an aquifer soil were investigated for 4 months in two phases including oxidant exposure (phase I) and biostimulation involving acetate addition (phase II). The geochemical and microbial alterations from different concentrations (0.2 and 50 mM) of hydrogen peroxide (HP) and peroxymonosulfate (PMS) were assessed. The 50 mM PMS-treated sample exhibited the most significant geochemical changes, characterized by the decrease in pH and the presence of more crystalline phases. Microbial activity decreased for all ISCO-treated microcosms compared to the controls; particularly, the activity was severely inhibited at high PMS concentration exposure. The soil microbial community structures were shifted after the ISCO treatment, with the high PMS causing the most distinct changes. Microbes such as the Azotobacter chroococcum and Gerobacter spp. increased during phase II of the ISCO treatment, indicating these bacterial communities can promote organic degradation despite the oxidants exposure. The HP (low and high concentrations) and low concentration PMS exposure temporarily impacted the microbial activity, with recovery after some duration, whereas the microbial activity was less recovered after the high concentration PMS exposure. These results suggest that the use of HP and low concentration PMS are suitable ISCO strategies for aquifer soil bioattenuation.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Azotobacter , Peróxido de Hidrogênio , Oxirredução , Peróxidos , Solo
13.
Nat Commun ; 12(1): 851, 2021 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-33558474

RESUMO

ATP-independent chaperones are usually considered to be holdases that rapidly bind to non-native states of substrate proteins and prevent their aggregation. These chaperones are thought to release their substrate proteins prior to their folding. Spy is an ATP-independent chaperone that acts as an aggregation inhibiting holdase but does so by allowing its substrate proteins to fold while they remain continuously chaperone bound, thus acting as a foldase as well. The attributes that allow such dual chaperoning behavior are unclear. Here, we used the topologically complex protein apoflavodoxin to show that the outcome of Spy's action is substrate specific and depends on its relative affinity for different folding states. Tighter binding of Spy to partially unfolded states of apoflavodoxin limits the possibility of folding while bound, converting Spy to a holdase chaperone. Our results highlight the central role of the substrate in determining the mechanism of chaperone action.


Assuntos
Trifosfato de Adenosina/metabolismo , Chaperonas Moleculares/metabolismo , Proteínas Periplásmicas/metabolismo , Anabaena/metabolismo , Apoproteínas/química , Apoproteínas/metabolismo , Azotobacter/metabolismo , Escherichia coli/metabolismo , Flavodoxina/química , Flavodoxina/metabolismo , Cinética , Espectroscopia de Ressonância Magnética , Conformação Molecular , Proteínas Mutantes/metabolismo , Proteínas Periplásmicas/química , Ligação Proteica , Dobramento de Proteína , Especificidade por Substrato
14.
Carbohydr Polym ; 255: 117384, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33436213

RESUMO

Prebiotics are known for their ability to modulate the composition of the human microbiome and mediate health-promoting benefits. Endo-levanases, which hydrolyze levan into short-chain FOS, could be used for the production of levan-based prebiotics. The novel endo-levanase (LevB2286) from Azotobacter chroococcum DSM 2286, combines an exceptionally high specific activity with advantageous hydrolytic properties. Starting from levan isolated from Timothy grass, LevB2286 produced FOS ranging from DP 2 - 8. In contrast to endo-levanases described in the literature, LevB2286 formed minor amounts of fructose and levanbiose, even with greatly extended incubation. The combined activity of LevB2286 and the levansucrase LevS1417 from Gluconobacter japonicus LMG 1417 led to a one-step synthesis of levan-type FOS from sucrose. 387.4 ± 17.3 g L-1 FOS were produced within 48 h by the production strategy based on crude cell extract of recombinant Escherichia coli expressing levS1417 and levB2286 simultaneously.


Assuntos
Azotobacter/enzimologia , Proteínas de Bactérias/metabolismo , Gluconobacter/enzimologia , Glicosídeo Hidrolases/metabolismo , Hexosiltransferases/metabolismo , Oligossacarídeos/biossíntese , Prebióticos/análise , Azotobacter/genética , Proteínas de Bactérias/genética , Dissacarídeos/química , Dissacarídeos/metabolismo , Escherichia coli/enzimologia , Escherichia coli/genética , Frutanos/química , Frutanos/metabolismo , Frutose/química , Frutose/metabolismo , Expressão Gênica , Gluconobacter/genética , Glicosídeo Hidrolases/genética , Hexosiltransferases/genética , Humanos , Hidrólise , Oligossacarídeos/química , Phleum/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Sacarose/química , Sacarose/metabolismo
15.
Int J Biol Macromol ; 168: 663-675, 2021 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-33220370

RESUMO

Given the excellent characteristics of alginate, it is an industrially important polysaccharide. Mannuronan C5-epimerase (MC5E) is an alginate-modifying enzyme that catalyzes the conversion of ß-D-mannuronate (M) to its C5 epimer α-L-guluronate (G) in alginate. Both the biological activities and physical properties of alginate are determined by M/G ratios and distribution patterns. Therefore, MC5E is regarded as a biotechnological tool for modifying and processing alginate. Various MC5Es derived from brown algae, Pseudomonas and Azotobacter have been isolated and characterized. With the rapid development of structural biology, the crystal structures and catalytic mechanisms of several MC5Es have been elucidated. It is necessary to comprehensively understand the research status of this alginate-modifying enzyme. In this review, the properties and potential applications of MC5Es isolated from different kinds of organisms are summarized and reviewed. Moreover, future research directions of MC5Es as well as strategies to enhance their properties are elucidated, highlighted, and prospected.


Assuntos
Alginatos/química , Carboidratos Epimerases/química , Carboidratos Epimerases/metabolismo , Azotobacter/enzimologia , Proteínas de Bactérias/metabolismo , Ácidos Hexurônicos/química , Feófitas/enzimologia , Conformação Proteica , Engenharia de Proteínas , Pseudomonas/enzimologia , Especificidade por Substrato
16.
J Appl Microbiol ; 131(1): 321-338, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33211366

RESUMO

AIM: The present research was conducted to investigate the effect of plant growth-promoting rhizobacteria (PGPR) and deficit irrigation on quality and quantity of flax under field and pot conditions to determine bacterial efficiency and to decrease water deficit effects. METHODS AND RESULTS: Initially, in vitro experiments were performed to determine the growth-promoting characteristics of bacteria. Then in the field, the effects of bacterial inoculation (control, Azotobacter chroococcum, Azospirillum lipoferum, Bacillus amyloliquefaciens, Bacillus sp. strain1 and Pseudomonas putida) on flax traits were evaluated at different irrigation levels (100, 75 and 50% crop water requirement). Bacterial treatments in the pot experiment were selected based on the field experiment results. The irrigation regimes in the pot and field experiments were the same and bacterial treatments included single, doublet and triplet applications of the bacteria. All the bacterial strains could solubilize phosphate, produce ammonia (except for Bacillus sp. strain1), indole acetic acid and siderophore (except P. putida). Field results indicated that the bacteria significantly mitigated the effects of water deficit. Compared with control plants, bacterial treatments increased the oil, linolenic acid, protein and sulphur content; the number of shoots and capsules; and the harvest index in the flax plants. Pot experimental results revealed that the combined inoculations were more effective than single inoculum treatments. CONCLUSIONS: Bacterial inoculation alleviates deficit irrigation effects in flax plants. SIGNIFICANCE AND IMPACT OF THE STUDY: The effectiveness of applying A. chroococcum, B. amyloliquefaciens and Bacillus sp. strain1 was confirmed, especially as a combination to protect flax against water deficit and to improve its nutritional quality and growth.


Assuntos
Azotobacter/fisiologia , Bacillus/crescimento & desenvolvimento , Linho/crescimento & desenvolvimento , Linho/microbiologia , Pseudomonas putida/fisiologia , Microbiologia do Solo , Irrigação Agrícola , Azotobacter/crescimento & desenvolvimento , Bacillus/fisiologia , Linho/metabolismo , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/microbiologia , Pseudomonas putida/crescimento & desenvolvimento
17.
Environ Pollut ; 269: 116218, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33316490

RESUMO

The current study for the first time demonstrates the interference of a free-living, N2-fixing, and nanoparticle (NP) tolerant Azotobacter salinestris strain ASM recovered from metal-polluted soil with tomato plant-metal oxide NPs (ZnO, CuO, Al2O3, and TiO2) interactions in a sandy clay loam soil system with bulk materials as control. Tomato plants were grown till full maturity in soils amended with 20-2000 mg kg-1 of each metal-oxide NP with and without seed biopriming and root-inoculation of A. salinestris. A. salinestris was found metabolically active, producing considerably high amounts of bioactive indole-3-acetic-acid, morphologically unaffected, and with low alteration of cell membrane permeability under 125-1500 µgml-1 of NPs. However, ZnO-NPs slightly alter bacterial membrane permeability. Besides, A. salinestris secreted significantly higher amounts of extracellular polymeric substance (EPS) even under NP exposure, which could entrap the NPs and form metal-EPS complex as revealed and quantified by SEM-EDX. NPs were also found adsorbed on bacterial biomass. EPS stabilized the NPs and provided negative zeta potential to NPs. Following soil application, A. salinestris improved the plant performance and augmented the yield of tomato fruits and lycopene content even in NPs stressed soils. Interestingly, A. salinestris inoculation enhanced photosynthetic pigment formation, flower attributes, plant and fruit biomass, and reduced proline level. Bacterial inoculation also reduced the NP's uptake and accumulation significantly in vegetative organs and fruits. The organ wise order of NP's internalization was roots > shoots > fruits. Conclusively, A. salinestris inoculation could be an alternative to increase the production of tomato in metal-oxide NPs contaminated soils.


Assuntos
Lycopersicon esculentum , Nanopartículas Metálicas , Nanopartículas , Poluentes do Solo , Óxido de Zinco , Azotobacter , Matriz Extracelular de Substâncias Poliméricas/química , Óxidos , Raízes de Plantas/química , Poluentes do Solo/análise
18.
Ying Yong Sheng Tai Xue Bao ; 31(10): 3413-3423, 2020 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-33314831

RESUMO

Understanding the dynamics of phosphate-solubilizing and N2-fixing bacteria on soil nutrient and related enzyme activity under different organic fertilizer proportions (OFP) could provide references for screening appropriate inoculant type, OFP, and fertilization period. Here, we set four OFP levels (mass ratio: 0%, 4%, 8%, 12%) and inoculated two phosphate-solubilizing bacteria (Bacillus megaterium, Pseudomonas fluorescens) and two N2-fixing bacteria (Azotobacter chroococcum, Azospirillum brasilence) in the subtropical yellow-brown barren soil. After a 60-day soil incubation under controlled conditions (28 ℃, darkness), we examined the impacts of single/mixed applications of beneficial bacteria on soil available nutrients and related enzyme activities at different OFP levels and different sampling times (3rd, 8th, 16th, 30th, 45th, 60th day). The results showed that soil available nutrient contents increased with the elevated OFP levels, and exhibited as 12%>8%>4%>0%. With the extension of culture time, soil nutrient contents in all treatments first increased and then decreased. Compared with the single application of organic fertilizer, combined application of organic fertilizer and bacterial inoculants resulted in higher and longer improvement of soil nutrient contents and enzyme activities. The effects of inoculants on soil nutrient properties varied across four OFP levels. When the OFP was low (0-4%), inoculation significantly increased soil available nutrient contents, with no the differences between inoculants at the initial stage. However, with the extension of the culture time and the elevation of OFP, phosphate-solubilizing bacteria (especially for B. megaterium) significantly increased available phosphorus content while N2-fixing bacteria (especially for A. brasilence) significantly increased available nitrogen content. The mixed inoculant with four strains showed phosphate-solubilizing effect on soil and performed better than the single application of phosphate-solubilizing bacteria, but without prominent effect on nitrogen fixation. Soil nutrient contents were positively correlated with enzyme activity, which was affected by both cultural time and carbon-nitrogen ratio. Bacterial inoculations could significantly increase nutrient contents in the short term, but the specific functions of beneficial bacteria on soil were highly dependent on organic carbon input and carbon-nitrogen ratio. Coupled application of inoculants and organic fertilizer at an appropriate OFP level (8%-12%) could increase and extend the soil-remediating effects, while the inoculation should be conducted with an interval of 45-60 days to ensure the survival rate and the consecutive effect on soil.


Assuntos
Fertilizantes , Bactérias Fixadoras de Nitrogênio , Azotobacter , Carbono , Fertilizantes/análise , Nitrogênio/análise , Nutrientes , Fosfatos , Solo , Microbiologia do Solo
19.
Pak J Biol Sci ; 23(11): 1456-1461, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33274875

RESUMO

BACKGROUND AND OBJECTIVE: The Damping-off disease is one of the most reasons for low productively of tomato in the world, especially in Iraq. In the current study, two types of bacteria (Azotobacter chroococcum and Pseudomonas fluorescens) were used to evaluate their efficacy in inhibiting the growth of pathogenic fungi Rhizoctonia solani and Fusarium solani and protecting the seeds of tomato and increasing their germination percentage. MATERIALS AND METHODS: Dual culture technique and Food poisoning technique were used to study the effect of bacteria on the growth of fungi understudy, and study the effect of bacterial filtrates on germination of tomato seeds. RESULTS: A. chroococcum showed the strongest antagonistic activity followed by P. fluorescens with the percentage of inhibition ranging between 72.9-77.1 and 69.5-70.3% for R. solani and F. solani respectively after 7 days of incubation. The effect of A. chroococcum and P. fluorescens filtrates were increased and also increased the inhibition of growth of fungi understudy, A. chroococcum filtrate also showed the strongest inhibitory effect followed by P. fluorescens with the percentage of inhibition ranging between 86.0-87.0 and 83.0-83.5% for R. solani and F. solani respectively at 20% concentration of filtrate. The percentage of seeds germination reached 90% in the treatment of A. chroococcum filtrate and 80% in the treatment of P. fluorescens filtrate. CONCLUSION: It can be concluded that the filtrates of A. chroococcum and P. fluorescens have antifungal properties against R. solani and F. solani and provided a high protection and increasing tomato seeds germination percentage.


Assuntos
Azotobacter/crescimento & desenvolvimento , Produtos Agrícolas/microbiologia , Fusarium/crescimento & desenvolvimento , Lycopersicon esculentum/microbiologia , Controle Biológico de Vetores , Doenças das Plantas/prevenção & controle , Pseudomonas fluorescens/crescimento & desenvolvimento , Rhizoctonia/crescimento & desenvolvimento , Produtos Agrícolas/crescimento & desenvolvimento , Fusarium/patogenicidade , Germinação , Lycopersicon esculentum/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Rhizoctonia/patogenicidade
20.
Pest Manag Sci ; 76(12): 4131-4140, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32706174

RESUMO

BACKGROUND: Nitrogen (N) is essential to crop yield improvement and it can change crops' ability to defend against herbivores. To maximize economic yield, a higher amount of N-fertilizer is often applied than the minimum required. Azotobacter is a good alternative to reduce N fertilizer application. In this study, we studied the yield and secondary defensive chemicals of maize, as well as the response of the key maize insect pest, Mythimna separata, as fed on maize plants inoculated with Azotobacter chroococcum and cultivated at different N fertilizer rates (i.e. the control rate of nitrogen fertilizer (CR), 80%CR and 60%CR) from 2018 to 2019. RESULTS: A. chroococcum inoculation just positively increased yield production of maize at 80%CR. Moreover, reduced N-fertilizer application and A. chroococcum inoculation had opposite impacts on the foliar contents of jasmonic acid (JA), isoleucine conjugate of JA (JA-Ile) and DIMBOA in maize, and they both negatively decreased the pupation rate and fecundity, and positively increased the eclosion rate and approximate digestibility (AD) of M. separata (P < 0.05). Furthermore, reduced N-fertilizer application negatively prolonged larval life-span, and decreased pupal weight, relative growth rate (RGR), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) of M. separata even A. chroococcum inoculation had positive effects on these indexes of M. separata (P < 0.05). CONCLUSION: These results help in understanding of the effects of low-level N-fertilizer and A. chroococcum inoculation on maize production and maize resistance to insects. This will be conducive to the integrated control of agricultural pests. © 2020 Society of Chemical Industry.


Assuntos
Azotobacter , Fertilizantes , Animais , Nitrogênio , Spodoptera , Zea mays
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