Decoding Bacillus spp.: Antimicrobial Diversity, Biocontrol Mechanisms, and Safe Deployment in Plant Disease Management

Chemical agents have long been used to control plant diseases, but their effects on the environment and lack of alignment with sustainable development goals are making them gradually unsuitable. One trend in green agriculture is the use of Bacillus species for the biocontrol of plant diseases. Due to their vast metabolic and genetic diversity, Bacillus spp. can contribute significantly to the soil ecosystem, while also enhancing plant resilience to biotic and abiotic stresses. Bacillus spp. are widely used in the agrobiotech industry due to their multi-functional versatility and are well-known for protecting plants from numerous plant diseases. In this review, we discussed the diversity and functions of antimicrobial compounds (AMCs) produced by Bacillus spp., along with their roles in plant growth promotion (PGP), and immunity. Furthermore, we highlighted the potential of Bacillus spp. as biopesticides in host plants, ways to enhance their biocontrol efficacy, and also addressed their possibility to cause disease in host plants. Considering the beneficial impacts of Bacillus spp. on PGP and pathogen biocontrol and their disease-causing capability, we discussed the possible solutions for a safe development of Bacillus-based biocontrol agent (BCA). Collectively, these insights can guide the selection of Bacillus strains with broad-spectrum or target-specific activity against pathogens, ensuring minimal adverse effects on the host.