Diversified populations of aerobic endospore forming bacteria (AEFB), viz.,
species of Bacillus, occur in agricultural fields and contribute to crop productivity
directly or indirectly. Physiological traits, such as multilayered cell wall, stress
resistant endospore formation, and secretion of peptide antibiotics, peptide signal
molecules, and extracellular enzymes, are ubiquitous to these bacilli and contribute
to their survival under adverse environmental conditions for extended periods of
time. Multiple species of Bacillus and Paenibacillus are known to promote plant
growth. The principal mechanisms of growth promotion include production
of growth stimulating phytohormones, solubilization and mobilization of phosphate,
siderophore production, antibiosis, i.e., production of antibiotics, inhibition
of plant ethylene synthesis, and induction of plant systemic resistance to
pathogens (Richardson et al. 2009; Idris et al. 2007; Gutierrez-Manero et al. 2001;