Abstract
BackgroundSymbiotic nitrogen fixation in plants occurs in roots with the help of some bacteria which help in soil nitrogen fertility management. Isolation of significant environment friendly bacteria for nitrogen fixation is very important to enhance yield in plants.ResultsIn this study effect of different magnetic field intensity and treatment time was studied on the morphology, physiology and nitrogen fixing capacity of newly isolated Paenibaccilus sp. from brown soil. The bacterium was identified by 16S rDNA sequence having highest similarity (99%) with Paenibacillus sp as revealed by BLAST. Different magnetic intensities such as 100mT, 300mT and 500mT were applied with processing time of 0, 5, 10, 20 and 30 minutes. Of all these treatment 300mT with processing time of 10 minutes was found to be most suitable treatment. Results revealed that magnetic treatment improve the growth rate with shorter generation time leading to increased enzyme activities (catalase, peroxidase and superoxide dismutase) and nitrogen fixing efficiencies. High magnetic field intensity (500mT) caused ruptured cell morphology and decreased enzyme activities which lead to less nitrogen fixation.ConclusionIt is concluded that appropriate magnetic field intensity and treatment time play a vital role in the growth of soil bacteria which increases the nitrogen fixing ability which affects the yield of plant. These results were very helpful in future breading programs to enhance the yield of soybean.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-015-0083-9) contains supplementary material, which is available to authorized users.
Highlights
Symbiotic nitrogen fixation in plants occurs in roots with the help of some bacteria which help in soil nitrogen fertility management
In 300 Magnetic field (mT) treatment the cell becomes thin and longer while in case of 500 mT treatment the cell membrane was ruptured and the cytoplasmic sap was released leading to the death of the Paenibacillus sp. These results revealed that suitable processing time with specific intensity can promote the growth of the Paenibacillus sp. but high and long time magnetic processing inhibited the growth leading to the death of Paenibacillus sp
I and II was 77% and 95% respectively. These results suggested that magnetic treatment time and intensity had strong influence on metabolic activity of Paenibacillus sp
Summary
Symbiotic nitrogen fixation in plants occurs in roots with the help of some bacteria which help in soil nitrogen fertility management. Paenibacillus genus of bacteria was first included in Bacillus genus and reclassified to a separate genus in 1993 (Ash et al 1993) These bacteria found in variety of environments like soil, water, forage, rhizosphere, insect larvae, vegetable matter and in clinical samples (McSpadden Gardener 2004, (Montes et al 2004; Ouyang et al 2008; Lal & Tabacchioni 2009)). These bacteria are of prime importance in agriculture for nitrogen fixation and industrial importance due to production of antibiotics and enzymes (Mavingui & Heulin 1994; Von der Weid et al 2003). It was necessary to study the rhizobia catalase, peroxidase and superoxide dismutase active changes
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