Role of Diazotrophic Bacteria in Biological Nitrogen Fixation and Plant Growth Improvement

다국어 초록 (Multilingual Abstract)

Though there is an abundant supply of nitrogen in the atmosphere, it cannot be used directly by the biological systems since it has to be combined with the element hydrogen before their incorporation. This process of nitrogen fixation (N₂-fixation) may be accomplished either chemically or biologically. Between the two elements, biological nitrogen fixation (BNF) is a microbiological process that converts atmospheric di-nitrogen (N₂) into plant-usable form. In this review, the genetics and mechanism of nitrogen fixation including genes responsible for it, their types and role in BNF are discussed in detail. Nitrogen fixation in the different agricultural systems using different methods is discussed to understand the actual rather than the potential N₂-fixation procedure. The mechanism by which the diazotrophic bacteria improve plant growth apart from nitrogen fixation such as inhibition of plant ethylene synthesis, improvement of nutrient uptake, stress tolerance enhancement, solubilization of inorganic phosphate and mineralization of organic phosphate is also discussed. Role of diazotrophic bacteria in the enhancement of nitrogen fixation is also dealt with suitable examples. This mini review attempts to address the importance of diazotrophic bacteria in nitrogen fixation and plant growth improvement.

목차 (Table of Contents)

• Introduction
• Discovery of nitrogen fixers
• Genetics of BNF
• The genes responsible for biological nitrogen fixation
• nifH as a marker gene
• Contribution of biological nitrogen fixation in nitrogen requirement
• Estimation of nitrogen fixation in the different agricultural systems
• Acetylene Reduction Assay
• Total nitrogen difference (TND) method
• N-solute Analysis of Xylem Exudate
• ¹⁵N Methods
• The diversity of diazotrophic bacteria
• Plant growth promotion by diazotrophic bacteria
• Conclusion
• References