A): The species of bacillus group, particularly B. Subtilus, B. Megaterium, B. Amyloliquefaciens, B. Lichniformis, and B. Pumilus are vital in agriculture, as phytopathogenic antagonists or plant growth promoters. This species is often referred to as “plant growth-promoting rhizobacteria “– PGPR.
PGPR are naturally occurring soil bacteria that have the ability to colonize the roots and stimulate plant growth by phytohormone production or by releasing beneficial organic compounds.
In addition to plant growth stimulation, Bacillus subtilis and its related species strains are involved in plant protection against Phyto-pathogenic attacks. They act directly against pathogens by producing extracellular lytic enzymes and secondary metabolites with inhibitory growth action or interfere via quorum quenching to disturb cell-to-cell communication of the infectious expression in pathogenic bacteria. They could also compete with plant pathogens for the available nutrient and niches. They also play a key role in the reduction of the infection process by inducing defense responses in the host plant.