Bioactive molecules from bacillus spp.: An effective tool for plant stress management

Abstract

The beneficial microbes are used to manage the plant diseases for sustainable agriculture production, which are alternatives to chemical fertilizers and pesticides. A key parameter in the effective management of plant disease is to protect the crop before the establishment of pathogen in an infection court. Recently, Bacillus species have been well demonstrated for its effectiveness against plant diseases, since it is most common bacteria found to colonize plants easily. Bacillus sp. inhibits the growth of phytopathogens directly or indirectly, through competition of space and nutrients. In addition, a wide variety of secondary metabolites are produced by Bacillus species that shows their ability as biocontrol agents against various plant diseases. Many potent Bacillus spp. possess secondary metabolites, including the difficidin, polyketides, and bacillaene. The Bacillus isolates produce several antimicrobial lipopeptides genes including fengycin, iturin, bacillomycin D, and surfactin. The resultant products of these molecules have been reported to inhibit fungal and bacterial diseases in crops. The indirect mode of action includes promoting plant growth and stimulation of the defense mechanism that trigger the first line of defense. These microbes have been known to facilitate a diverse mechanisms like quorum sensing (QS) for plant signal interference, production of volatile organic compounds (VOCs), displaying antimicrobial activity and induction of systemic resistance, thereby promoting beneficial plant-microbe interactions. Besides, the endospore-forming ability of the bacteria enhances their survival capability under diverse environmental conditions. Lastly, the antibiotic production induced resistance and growth promotion action mediated by Bacillus spp. as an effective management tool for plant disease control, since it is durable and environment-friendly alternative for chemical-based plant disease management.