Significance of Cyanobacteria in Soil-Plant System and for Ecological Resilience

Cyanobacteria are unique group of photosynthetic gram-negative prokaryotes. They are precious bio-resource option for sustainable development of agriculture. Cyanobacteria belong to blue green algae, and they can survive under minimum presence of light, carbon dioxide and water. Apart from their primary role in fixing atmospheric nitrogen and improving soil nutrient status, they can deliver multifaceted but unique tasks like production of plant growth promoting bioactive molecules, bioremediation of heavy metals, decomposition of organic residues, generation of high valued biological substances, etc. They also have the potential to act as bio-control agents against several plant pathogenic bacteria or fungi. Further, they can help to curb CO2 loading in atmosphere by enhancing soil methane sink through methanotrophic diversity. Cyanobacteria also exude extracellular polysaccharides that increase activity of nutrient-liberating enzymes and induce growth promotion of other beneficial soil-microbes. They help to improve structural stability of soil by holding soil particles together, particularly when their biomass get incorporated into soil. Cyanobacteria, by forming consortia with other plant growth promoting rhizobacteria, increase plant growth and also enhance tolerance of plants to various environmental stresses. For these reasons, cyanobacteria are considered as a key factor towards the betterment of soil health and ecological resilience.