Archaea, bacteria and termite, nitrogen fixation and sustainable plants production

Abstract

Certain bacteria and archaea are responsible for biological nitrogen fixation. Metabolic pathways usually are common between archaea and bacteria. Diazotrophs are categorized into two main groups namely: root-nodule bacteria and plant growth-promoting rhizobacteria. Diazotrophs include free living bacteria, such as Azospirillum, Cupriavidus, and some sulfate reducing bacteria, and symbiotic diazotrophs such Rhizobium and Frankia. Three types of nitrogenase are iron and molybdenum (Fe/Mo), iron and vanadium (Fe/V) or iron only (Fe). The Mo-nitrogenase have a higher specific activity which is expressed better when Molybdenum is available. The best hosts for Rhizobium legumiosarum are Pisum, Vicia, Lathyrus and Lens; Trifolium for Rhizobium trifolii; Phaseolus vulgaris, Prunus angustifolia for Rhizobium phaseoli; Medicago, Melilotus and Trigonella for Rhizobium meliloti; Lupinus and Ornithopus for Lupini, and Glycine max for Rhizobium japonicum. Termites have significant key role in soil ecology, transporting and mixing soil. Termite gut microbes supply the enzymes required to degrade plant polymers, synthesize amino acids, recycle nitrogenous waste and fix atmospheric nitrogen. The positive effects of Arbuscular mycorrhizal (AM) fungi such as growth promotion, increased root length, leaf area, stem diameter, transplant performance and tolerance to stresses have been reported previously.