-
Current Microbiology Jul 2022Climate change is emerging as a crucial issue with global attention and leading to abiotic stress conditions. There are different abiotic stress which affects the crop... (Review)
Review
Climate change is emerging as a crucial issue with global attention and leading to abiotic stress conditions. There are different abiotic stress which affects the crop production among which drought is known to be most destructive stress affecting crop productivity and world's food security. Different approaches are under consideration to increase adaptability of the plants under drought stress with plant-microbe interactions being a greater area of focus. Stress-adaptive microbes either from the rhizosphere, internal tissue, or aerial parts of plants have been reported which through different mechanisms help the plants to cope up with drought and also promote their growth. These mechanisms include the accumulation of osmolytes, decrease in the inhibitory levels of ethylene by aminocyclopropane-1-carboxylate (ACC) deaminase enzyme, and furnishing the unavailable nutrients to plants. Microbial genera including Azotobacter, Bacillus, Ochrobactrum, Pseudomonas, and Serratia are known to be self-adaptive and growth promoters under drought stressed conditions. Stress-adaptive plant growth promoting (PGP) microbes thus are excellent candidates for stress alleviation in drought environment to provide maximum benefits to the plants. The present review deals with the effect of the drought stress on plants, biodiversity of the drought-adaptive microbes, mechanisms of the drought stress alleviation through enhancement of stress alleviators, reduction of the stress aggravators, and modification of the molecular pathways as well as the multiple PGP attributes of the drought-adaptive microbes.
Topics: Bacteria; Droughts; Plant Development; Plant Roots; Plants; Rhizosphere; Soil Microbiology; Stress, Physiological
PubMed: 35834053
DOI: 10.1007/s00284-022-02939-w -
Nature Communications Feb 2023Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia during the process of biological nitrogen fixation that is essential for sustaining life. The...
Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia during the process of biological nitrogen fixation that is essential for sustaining life. The active site FeMo-cofactor contains a [7Fe:1Mo:9S:1C] metallocluster coordinated with an R-homocitrate (HCA) molecule. Here, we establish through single particle cryoEM and chemical analysis of two forms of the Azotobacter vinelandii MoFe-protein - a high pH turnover inactivated species and a ∆NifV variant that cannot synthesize HCA - that loss of HCA is coupled to α-subunit domain and FeMo-cofactor disordering, and formation of a histidine coordination site. We further find a population of the ∆NifV variant complexed to an endogenous protein identified through structural and proteomic approaches as the uncharacterized protein NafT. Recognition by endogenous NafT demonstrates the physiological relevance of the HCA-compromised form, perhaps for cofactor insertion or repair. Our results point towards a dynamic active site in which HCA plays a role in enabling nitrogenase catalysis by facilitating activation of the FeMo-cofactor from a relatively stable form to a state capable of reducing dinitrogen under ambient conditions.
Topics: Nitrogenase; Proteomics; Molybdoferredoxin; Tricarboxylic Acids; Azotobacter vinelandii
PubMed: 36841829
DOI: 10.1038/s41467-023-36636-4 -
Applied Microbiology and Biotechnology Nov 2023The continuous obstacles of cropping cause severe economic loss, which seriously threaten agricultural sustainable development. In addition, managing excess waste, such...
The continuous obstacles of cropping cause severe economic loss, which seriously threaten agricultural sustainable development. In addition, managing excess waste, such as potato peel and mineral waste residues, is a vital burden for industry and agriculture. Therefore, we explored the feasibility of reductive soil disinfestation (RSD) with potato peel and amendment with iron mineral waste residues for the production of Fritillaria thunbergii, which is vulnerable to continuous obstacles. In this study, the influences of iron mineral, RSD with different organic maters, as well as the combined effects of iron mineral and RSD on Fritillaria rhizosphere soil physicochemical properties, microbial communities, and Fritillaria production were investigated. The results revealed that the RSD treatments with potato peel significantly reduced the soil salinity and increased the soil pH, microbial activity, organic matter, and the contents of K and Ca. RSD with potato peel also significantly thrived of the beneficial microbes (Bacillus, Azotobacter, Microvirga, and Chaetomium), and down-regulated potential plant pathogens. RSD with potato peel significantly promoted F. thunbergii yield and quality. Moreover, the combined effects of RSD and iron mineral amendment further enhanced soil health, improved microbial community composition, and increased the yield and peimisine content of F. thunbergii by 24.2% and 49.3%, respectively. Overall, our results demonstrated that RSD with potato peel and amendment with iron mineral waste residues can efficiently improve soil fertility, modify the microbial community, and benefit for both the sustainable production of F. thunbergii and the management of waste. KEY POINTS: • RSD increases soil pH, organic matter, microbial activity, and mineral content • RSD with potato peel enriches beneficial microbes and decreases plant pathogens • PP + Fe treatment increases Fritillaria yield by 24.2% and peimisine content by 49.3.
PubMed: 37676290
DOI: 10.1007/s00253-023-12766-z -
Scientific Reports Sep 2022Licorice (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...
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.
Topics: Azotobacter; Flavonoids; Glycyrrhiza; Glycyrrhizic Acid; Iran; Phenols; Plant Extracts; Plant Roots; Rutin; Salinity; Salt Stress; Sodium Chloride; Sugars; Triterpenes
PubMed: 36151202
DOI: 10.1038/s41598-022-20366-6 -
International Journal of Molecular... Sep 2022Due to the observed climate warming, water deficiency in soil is currently one of the most important stressors limiting the size and quality of plant crops. Drought...
Due to the observed climate warming, water deficiency in soil is currently one of the most important stressors limiting the size and quality of plant crops. Drought stress causes a number of morphological, physiological, and biochemical changes in plants, limiting their growth, development, and yield. Innovative methods of inducing resistance and protecting plants against stressors include the inoculation of crops with beneficial microorganisms isolated from the rhizosphere of the plant species to which they are to be applied. The aim of the present study was to evaluate 12 different strains of rhizosphere bacteria of the genera , , , and by using them to inoculate strawberry plants and assessing their impact on mitigating the negative effects of drought stress. Bacterial populations were assessed by estimates of their size based on bacterial counts in the growth substrate and with bioassays for plant growth-promoting traits. The physiological condition of strawberry plants was determined based on the parameters of chlorophyll fluorescence. The usefulness of the test methods used to assess the influence of plant inoculation with rhizosphere bacteria on the response of plants growing under water deficit was also evaluated. A two-factor experiment was performed in a complete randomization design. The first experimental factor was the inoculation of plant roots with rhizosphere bacteria. The second experimental factor was the different moisture content of the growth substrate. The water potential was maintained at -10 to -15 kPa under control conditions, and at -40 to -45 kPa under the conditions of water deficit in the substrate. The tests on strawberry plants showed that the highest sensitivity to water deficiency, and thus the greatest usefulness for characterizing water stress, was demonstrated by the following indices of chlorophyll "a" fluorescence: F, F, F/F, PI, and Area. Based on the assessment of the condition of the photosynthetic apparatus and the analysis of chlorophyll "a" fluorescence indices, including hierarchical cluster analysis, the following strains of rhizosphere bacteria were found to have favorable effects on strawberry plants under water deficit: the sp. strains DLGB2 and DKB26 and the sp. strains DKB63, DKB70, DKB68, DKB64, and DKB65. In the tests, these strains of sp. exhibited a common trait-the ability to produce siderophores, while those of sp. were notable for phosphate mobilization and ACCD activity.
Topics: Bacillus; Bacteria; Chlorophyll; Crops, Agricultural; Fragaria; Phosphates; Plant Roots; Rhizosphere; Siderophores; Soil; Soil Microbiology
PubMed: 36142361
DOI: 10.3390/ijms231810449 -
Foods (Basel, Switzerland) Sep 2022The use of microbial biostimulants such as plant growth-promoting rhizobacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) has gained popularity in recent years as a... (Review)
Review
The use of microbial biostimulants such as plant growth-promoting rhizobacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) has gained popularity in recent years as a sustainable approach to boost yield as well as the quality of produce. The beneficial effects of microbial biostimulants have been reported numerous times. However, information is missing concerning quantitative assessment of the overall impact of microbial biostimulants on the yield and quality of vegetable crops. Here we provide for the first time a comprehensive, semi-systematic review of the effects of microbial biostimulants allowed by Regulation (EU) 2019/1009, including microorganisms belonging to the AMF (phylum Glomeromycota), or to , and genera, on vegetable crops' quality and yield, with rigorous inclusion and exclusion criteria based on the PRISMA method. We identified, selected and critically evaluated all the relevant research studies from 2010 onward in order to provide a critical appraisal of the most recent findings related to these EU-allowed microbial biostimulants and their effects on vegetable crops' quality and yield. Moreover, we highlighted which vegetable crops received more beneficial effects from specific microbial biostimulants and the protocols employed for plant inoculation. Our study is intended to draw more attention from the scientific community to this important instrument to produce nutrient-dense vegetables in a sustainable manner. Finally, our semi-systematic review provides important microbial biostimulant application guidelines and gives extension specialists and vegetable growers insights into achieving an additional benefit from microbial biostimulant application.
PubMed: 36076841
DOI: 10.3390/foods11172656 -
Plants (Basel, Switzerland) Feb 2022Vegetables can be treated with biofertilizers as an alternative to chemical fertilizers because of their low toxicity. We investigated the effects of foliar spraying of...
Vegetables can be treated with biofertilizers as an alternative to chemical fertilizers because of their low toxicity. We investigated the effects of foliar spraying of under different levels of nitrogen (100, 150 and 200 mg/L in nutrient solution) on the growth, nutritional value, nitrate accumulation and antioxidant enzyme activities of hydroponically grown lettuce. The experiment was laid out in a completely randomized design with four replicates in a factorial combination. Plants treated with and 200 mg/L nitrogen had greater leaf area and photosynthetic pigments than plants treated with 200 mg/L nitrogen without spraying with . Increasing nitrogen levels increased leaf number, fresh and dry weights, leaf area and nitrate accumulation in lettuce plants. Peroxidase (POD) activity increased by 95.4% at a nitrogen level of 200 mg/L compared to a nitrogen level of 100 mg/L. Ascorbate peroxidase (APX) activity and leaf phosphorous (P) and potassium (K) concentrations were the highest in plants treated with a nitrogen source of 100 mg/L without foliar application of . As nitrogen levels increased in all treatments, nitrate reductase (NR) activity decreased and reached a minimum at the 200 mg/L nitrogen level. In general, foliar application of sp. can be used to promote plant growth and reduce nitrate accumulation in lettuce.
PubMed: 35161387
DOI: 10.3390/plants11030406 -
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 -
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