Antimicrobial metabolites produced by the plant growth-promoting rhizobacteria (PGPR): Bacillus and Pseudomonas

Plant growth-promoting rhizobacteria (PGPR) such as Bacillus and Pseudomonas have drawn broad attention and interest due to their agricultural benefits. One of the major benefits of PGPR lies at their biocontrol capabilities against various plant pathogens. The biocontrol capability of PGPR is closely related to its capability of producing various kinds of antimicrobial substances. Major antimicrobial secondary metabolites secreted by PGPR include non-ribosomal lipopeptides (NRLPs), polyketides, ribosomal peptides, phenazines, pyrrolnitrins, etc. This review focuses on the major antimicrobial secondary metabolites produced by Bacillus and Pseudomonas including their classifications, structures, mechanisms of action and genetic regulations. We have also discussed their applications in plant biocontrol and provided insights into future development of improved biocontrol strains using synthetic biology approaches.