scholarly journals Studies on nitrogen fixation by machete-resistant mutant strains of Azospirillum brasilense: Their associative N2-fixation and yield response of rice to root inoculation in calcareous soil.

1985 ◽  
Vol 31 (1) ◽  
pp. 1-16 ◽  
Author(s):  
RAMAN RAI
Keyword(s):  
Nitrogen Fixation ◽  
N2 Fixation ◽  
Azospirillum Brasilense ◽  
Calcareous Soil ◽  
Resistant Mutant ◽  
Yield Response ◽  
Mutant Strains ◽  
Associative N2 Fixation

Studies on nitrogen fixation by antibiotic-resistant mutants ofAzospirillum brasilenseand their interaction with cheena (Panicum miliaceumL.) genotypes in calcareous soil

1985 ◽  
Vol 105 (2) ◽  
pp. 261-270 ◽  
Author(s):  
R. Rai
Keyword(s):  
Nitrogen Fixation ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Hydrogenase Activity ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Antibiotic Resistant ◽  
Mutant Strains

SUMMARYAzospirillum brasilense was treated with nitrosoguanidine and five antibiotic-resistant mutant strains isolated. Variations in growth, N2-fixation, ultraviolet-dark survival and level of antibiotic resistance were found between the mutant strains. Mutant strains STR 112 and KR 2051 showed maximum nitrogenase activity, glutamine synthetase activity and hydrogenase activity (H2uptake) at 32 °C and 40 °C respectively. Inoculation of cheena genotypes withA. brasilenseand its mutants led to significant increase in associative nitrogen fixation, dry weight of roots and grain yield compared with the uninoculated control, with significant strains × genotypes interactions in calcareous soil. It was also noted that under laboratory conditionsAzospirilluminoculation may have produced its response by hormonal means and/or associative N2-fixation.

Studies on associative nitrogen fixation by antibiotic-resistant mutants ofAzospirillum brasilensewith genotypes of lentil (Lens culinaris)Rhizobiumstrains in calcareous soil

1985 ◽  
Vol 104 (1) ◽  
pp. 207-215 ◽  
Author(s):  
R. Rai
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Calcareous Soil ◽  
Lens Culinaris ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Antibiotic Resistant ◽  
Uninoculated Control ◽  
Resistant Mutants ◽  
Antibiotic Resistant Mutants

SummaryNitrosoguanidine-induced mutation frequencies for resistance to streptomycin, spectinomycin, erythromycin and novomycin were studied inAzospirillum brasilense.Lentil inoculated withA. brasilenseand its mutants andRhizobiumstrains produced increased nodule dry weight, nitrogenase activity of nodules and roots and grain yield compared with an uninoculated control.

Phorate-resistant mutant strains of chick pea (Cicer arietinumL.)Rhizobiumsp. growth and their compatibility in symbiotic nitrogen fixation

1982 ◽  
Vol 98 (3) ◽  
pp. 547-551 ◽  
Author(s):  
R. Rai ◽  
R. B. Sinha ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
Grain Yield ◽  
Symbiotic Nitrogen Fixation ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Pyridine Nucleotides ◽  
Chick Pea ◽  
Active Iron ◽  
Mutant Strains

SUMMARYChick peaRhizobiumstrain RG3 was treated with 30 μg/ml of N-nitrosoguanidine and two mutants isolated were resistant to 2000 μg phorate/ml yet retained the capacity to form nodules. On the basis of number of nodules, their dry weight, N2ase activity, total pyridine nucleotides and active iron contents, mutant strains G11 and G26 were found to be equally effective with and without phorate and resulted in significantly greater grain yield.

Interaction between finger millet (Eleusine coracana) genotypes and drug-resistant mutants ofAzospirillum brasilensein calcareous soil

1984 ◽  
Vol 102 (3) ◽  
pp. 521-529 ◽  
Author(s):  
R. Rai ◽  
V. Prasad ◽  
I. C. Shukla
Keyword(s):  
Azospirillum Brasilense ◽  
Finger Millet ◽  
Nitrogenase Activity ◽  
Resistant Mutant ◽  
Eleusine Coracana ◽  
Drug Resistant ◽  
Mutant Strains ◽  
Drug Resistant Mutant ◽  
Uninoculated Control ◽  
Resistant Mutants

SummaryAzospirillum brasilensewas treated with nitrosoguanidine and five drug-resistant mutant strains isolated. The effects of acriflavin on pre- and post-irradiation with u.v. light and the level of antibiotic resistance were studied. Variations in factors were found between the strains. Inoculation of finger millet withA. brasilenseand mutant strains led to significant increases in grain yield and nitrogenase activity compared with the uninoculated control, with significant strain x genotype interactions. Differential response of genotype and strain was noted on the protein and amino acid concentration of seeds.

Competitiveness and effectiveness of carbendazim-resistant mutant and indigenous Rhizobiumstrains of chick pea (Cicer arietinutnLinn.) in calcareous soil

1985 ◽  
Vol 104 (2) ◽  
pp. 341-344 ◽  
Author(s):  
R. Rai
Keyword(s):  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Triphenyl Tetrazolium Chloride ◽  
Tetrazolium Chloride ◽  
Chick Pea ◽  
Active Iron ◽  
Mutant Strains

SummaryChick pea Rhizobiumstrain RG 4 was treated with 30 /tg/ml of N-nitrosoguanidine and four mutants isolated were resistant to 400 /tg carbendazim/ml. Only two of the mutants (M 1 and M 4) retained the capacity to form nodules. On the basis of number of nodules, their dry weight, nitrogenase activity, triphenyl tetrazolium chloride reductase activity and active iron content of nodules, mutant strains M 1 and M 4 were found to be equally effective for nitrogen fixation both with and without carbendazim (bavistine) and resulted in significantly greater grain yield than the corresponding uninoculated treatments.

Effect of inoculation of Zea mays with Azospirillum brasilense strains under temperate conditions

1981 ◽  
Vol 27 (9) ◽  
pp. 871-877 ◽  
Author(s):  
G. W. O'Hara ◽  
M. R. Davey ◽  
J. A. Lucas
Keyword(s):  
Zea Mays ◽  
Nitrogen Content ◽  
Acetylene Reduction ◽  
Azospirillum Brasilense ◽  
Dry Weight ◽  
Yield Response ◽  
Acetylene Reduction Activity ◽  
Reduction Activity ◽  
Mutant Strains ◽  
Nitrogen Concentrations

Seven strains of Azospirillum brasilense were compared for their effect on the growth of Zea mays grown under temperate conditions in sand–vermiculite pot cultures. Inoculation with all seven strains tested, including Fix− mutant strains, increased dry weight and total nitrogen content of shoots, but nitrogen concentrations were unaffected. Low and variable rates of acetylene reduction activity were observed from excised roots of inoculated plants without preincubation. Estimates of N2-fixing A. brasilense associated with inoculated roots showed differences between strains in establishing themselves in the rhizosphere and endorhizosphere. In some strains enrichment in the endorhizosphere of roots occurred following inoculation, but the relative numbers and location of the strains did not appear to affect the yield response.

Efficacy of associative N2-fixation by streptomycin-resistant mutants ofAzospirillum brasilensewith genotypes of chick peaRhizobiumstrains

1983 ◽  
Vol 100 (1) ◽  
pp. 75-80 ◽  
Author(s):  
R. Rai
Keyword(s):  
Grain Yield ◽  
N2 Fixation ◽  
Iron Content ◽  
Azospirillum Brasilense ◽  
Dry Weight ◽  
Chick Pea ◽  
Active Iron ◽  
Ultraviolet Sensitivity ◽  
Associative N2 Fixation ◽  
Resistant Mutants

SUMMARYAzospirillum brasilensewas treated with nitrosoguanidine and two mutants isolated which were resistant to 500 μg streptomycin/ml. Ultraviolet sensitivity, photoreactivation and effect of acriflavin on pre- and post-irradiation were studied. Chick pea showed an increase in grain yield, nodule dry weight, N2ase activity and active iron content of nodules when inoculated withA. brasilenseor its mutants together withRhizobium. The interaction betweenRhizobiumstrains and genotypes of chick pea was significant.

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.

Studies on compatibility of nitrogen fixation by high-temperature-adapted Rhizobium strains and Vigna radiata genotypes at two moisture levels in calcareous soil

1983 ◽  
Vol 101 (2) ◽  
pp. 377-381 ◽  
Author(s):  
R. Rai ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
High Temperature ◽  
Grain Yield ◽  
Vigna Radiata ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Summer Season ◽  
Green Gram ◽  
Rhizobium Strains

SUMMARYRhizobium strains adapted to high temperature, and genotypes of green gram, were used to study the symbiotic N2-fixation in a summer season at two moisture levels in calcareous soil. Different interactions between strains and genotypes were observedatthe two moisture levels. At both moisture levels, strain S4 with the green gram genotype S8 showed the greatest grain yield, nitrogenase activity, leghaemoglobin and ethanolsoluble carbohydrate of nodules.

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