scholarly journals Molecular Evolution of the Negative Regulatory Gene (NIFL) from Azotobacter Chroococcum and its Nitrogenase Activity

2018 ◽  
Vol 15 (2) ◽  
pp. 397-406
Author(s):  
Gothandapani Sellamuthu ◽  
Prabha Shankar ◽  
Sekar Soundarapandian ◽  
Sangeeta Paul ◽  
Jasdeep C. Padaria
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Source ◽  
Genetic Manipulation ◽  
Nitrogenase Activity ◽  
Inorganic Nitrogen ◽  
Regulatory Gene ◽  
Azotobacter Chroococcum ◽  
Inorganic Nitrogen Source ◽  
Plant Growth Promoting ◽  
Growth Promoting

Two isolates of Azotobacter chroococcum (A. chroococcum CBD15 and A. chroococcum W5), were characterized for their atmospheric nitrogen fixing efficiency and ability to produce plant growth promoting hormone. The isolates, A. chroococcum CBD15 and A. chroococcum W5, were observed the production of Indole acetic acid (IAA) and nitrogen fixation in the absence of any inorganic nitrogen source. The ability nitrogen fixation was estimated by acetylene reduction studies revealed that A. chroococcum CBD15 produced 693.3 nmole C2H4 h-1 mg-1 whereas A. chroococcum W5 produced 523.4 nmole C2H4 h-1 mg-1. Nitrogenase activity of both the isolates was reduced when grown in media containing nitrogen source (ammonia or urea), in comparison to media lacking any nitrogen source. The nifL gene, which is one of the most important regulatory gene of nitrogen fixation pathway, was isolated from A. chroococcum CBD15 and A. chroococcum W5. Sequence analysis revealed that both nifL gene sequences have maximum homology with nifL gene of A. vinelandii and Pseudomonas oryzae respectively. The genetic manipulation of nifL gene of A. chrococcum will lead to development of an efficient bioinoculant for sustainable agriculture.

A Study on the Farmers’ Awareness and Acceptance of Biofertilizers in Kottayam District

GIS Business ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. 425-431
Author(s):  
Subin Thomas ◽  
Dr. M. Nandhini
Keyword(s):  
Organic Matter ◽  
Nitrogen Fixation ◽  
Plant Growth ◽  
Plant Growth Promoting Rhizobacteria ◽  
Nutrient Cycle ◽  
Plant Growth Promoting ◽  
Promote Plant Growth ◽  
Growth Promoting ◽  
Structured Questionnaire ◽  
Area Data

Biofertilizers are fertilizers containing microorganisms that promote plant growth by improving the supply of nutrients to the host plant. The supply of nutrients is improved naturally by nitrogen fixation and solubilizing phosphorus. The living microorganisms in biofertilizers help in building organic matter in the soil and restoring the natural nutrient cycle. Biofertilizers can be grouped into Nitrogen-fixing biofertilizers, Phosphorous-solubilizing biofertilizers, Phosphorous-mobilizing biofertilizers, Biofertilizers for micro nutrients and Plant growth promoting rhizobacteria. This study conducted in Kottayam district was intended to identify the awareness and acceptance of biofertilizers among the farmers of the area. Data have been collected from 120 farmers by direct interviews with structured questionnaire.

scholarly journals Genomic characterization and computational phenotyping of nitrogen-fixing bacteria isolated from Colombian sugarcane fields

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luz K. Medina-Cordoba ◽  
Aroon T. Chande ◽  
Lavanya Rishishwar ◽  
Leonard W. Mayer ◽  
Lina C. Valderrama-Aguirre ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Nitrogen Fixation ◽  
Plant Growth ◽  
Phosphate Solubilization ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Promising Tool ◽  
A Genome ◽  
Plant Growth Promoting ◽  
Growth Promoting

AbstractPrevious studies have shown the sugarcane microbiome harbors diverse plant growth promoting microorganisms, including nitrogen-fixing bacteria (diazotrophs), which can serve as biofertilizers. The genomes of 22 diazotrophs from Colombian sugarcane fields were sequenced to investigate potential biofertilizers. A genome-enabled computational phenotyping approach was developed to prioritize sugarcane associated diazotrophs according to their potential as biofertilizers. This method selects isolates that have potential for nitrogen fixation and other plant growth promoting (PGP) phenotypes while showing low risk for virulence and antibiotic resistance. Intact nitrogenase (nif) genes and operons were found in 18 of the isolates. Isolates also encode phosphate solubilization and siderophore production operons, and other PGP genes. The majority of sugarcane isolates showed uniformly low predicted virulence and antibiotic resistance compared to clinical isolates. Six strains with the highest overall genotype scores were experimentally evaluated for nitrogen fixation, phosphate solubilization, and the production of siderophores, gibberellic acid, and indole acetic acid. Results from the biochemical assays were consistent and validated computational phenotype predictions. A genotypic and phenotypic threshold was observed that separated strains by their potential for PGP versus predicted pathogenicity. Our results indicate that computational phenotyping is a promising tool for the assessment of bacteria detected in agricultural ecosystems.

Stimulation of dextranase production by oxidized dextran

1970 ◽  
Vol 16 (9) ◽  
pp. 841-844 ◽  
Author(s):  
Robert G. Brown
Keyword(s):  
Carbon Source ◽  
Nitrogen Source ◽  
Enzyme Production ◽  
Inorganic Nitrogen ◽  
Penicillium Funiculosum ◽  
Inorganic Nitrogen Source ◽  
Oxidized Dextran ◽  
Excess Glucose ◽  
Stimulation Of

Penicillium funiculosum, Penicillium lilacinum, and Spicaria violacea produced excellent yields of dextranase if ketodextran replaced dextran as a carbon source. Ketodextrans I and II having degrees of substitution of 2 and 20% respectively were used in this study. P. funiculosum grew equally well on dextran and ketodextran I but less well on ketodextran II. Addition of a readily metabolizable carbohydrate such as glucose, sucrose, or galactose stimulated growth on ketodextran II, resulting in better dextranase production. However, excess glucose reversed this increase in enzyme production. Replacement of an inorganic nitrogen source with an organic one further stimulated dextranase production during growth of P. funiculosum on ketodextran II.

scholarly journals Characterization of Arsenic-Resistant Endophytic Bacteria From Alfalfa and Chickpea Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Hazhir Tashan ◽  
Behrouz Harighi ◽  
Jalal Rostamzadeh ◽  
Abdolbaset Azizi
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Endophytic Bacteria ◽  
Phosphate Solubilization ◽  
Lipase Production ◽  
Growth Potential ◽  
Sodium Arsenate ◽  
Plant Growth Promoting ◽  
Growth Promoting

The present investigation was carried out to isolate arsenic (As)-resistant endophytic bacteria from the roots of alfalfa and chickpea plants grown in arsenic-contamination soil, characterize their As tolerance ability, plant growth-promoting characteristics, and their role to induce As resistance by the plant. A total of four root endophytic bacteria were isolated from plants grown in As-contaminated soil (160–260-mg As kg−1 of soil). These isolates were studied for plant growth-promoting (PGP) characteristics through siderophore, phosphate solubilization, nitrogen fixation, protease, and lipase production, and the presence of the arsenate reductase (arsC) gene. Based on 16S rDNA sequence analysis, these isolates belong to the genera Acinetobacter, Pseudomonas, and Rahnella. All isolates were found As tolerant, of which one isolate, Pseudomonas sp. QNC1, showed the highest tolerance up to 350-mM concentration in the LB medium. All isolates exhibited phosphate solubilization activity. Siderophore production activity was shown by only Pseudomonas sp. QNC1, while nitrogen fixation activity was shown by only Rahnella sp. QNC2 isolate. Acinetobacter sp. QNA1, QNA2, and Rahnella sp. QNC2 exhibited lipase production, while only Pseudomonas sp. QNC1 was able to produce protease. The presence of the arsC gene was detected in all isolates. The effect of endophytic bacteria on biomass production of alfalfa and chickpea in five levels of arsenic concentrations (0-, 10-, 50-, 75-, and 100-mg kg−1 soil) was evaluated. The fresh and dry weights of roots of alfalfa and chickpea plants were decreased as the arsenic concentration of the soil was increased. Results indicate that the fresh and dry root weights of alfalfa and chickpea plants were significantly higher in endophytic bacteria-treated plants compared with non-treated plants. Inoculation of chickpea plants with Pseudomonas sp. QNC1 and Rahnella sp. QNC2 induced lower NPR3 gene expression in chickpea roots grown in soil with the final concentration of 100-mg kg−1 sodium arsenate compared with the non-endophyte-treated control. The same results were obtained in Acinetobacter sp. QNA2-treated alfalfa plants grown in the soil plus 50-mg kg−1 sodium arsenate. These results demonstrated that arsenic-resistant endophytic bacteria are potential candidates to enhance plant-growth promotion in As contamination soils. Characterization of bacterial endophytes with plant growth potential can help us apply them to improve plant yield under stress conditions.

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