Mining the underlying biocontrol mechanism of native Bacillus amyloliquefaciens WS-10 against tobacco bacterial wilt disease

Ralstonia solanacearum, the causative agent of bacterial wilt disease, is an ever-increasing threat to tobacco production globally. Thus, there is an intense need to find an effective control measure to manage this disease. This study explored the in-depth biocontrol mechanism of Bacillus amyloliquefaciens WS-10 to manage tobacco bacterial wilt disease through high throughput sequencing. In vitro conditions, B. amyloliquefaciens WS-10 shows potent antifungal activity against many phytopathogenic fungi, forms biofilm, and secrete hydrolytic enzymes. In planta assays, B. amyloliquefaciens WS-10 successfully colonized in tobacco plant roots and rhizosphere soil and significantly mitigated tobacco bacterial wilt disease up to 72.02% by reducing the population of R. solanacearum. Amplification of V3-V4 and ITS1 variable regions of 16S and ITS rRNA showed that B. amyloliquefaciens WS-10 influences the microbial community composition and dramatically changes the rhizosphere microbial diversity and structure. A complex microbial co-occurrence network under a diseased state proved that microbial communities accelerate disease development. The presence of genes related to antimicrobial lipopeptides (fenA, ituC, srfA, and bmyA) and polyketides (dfnA, bacA, dhbA, and beaS) were analyzed. Interestingly, the genome of B. amyloliquefaciens WS-10 contains all these genes and produces antimicrobial compounds. Our study showed the potential of B. amyloliquefaciens WS-10 to mitigate bacterial wilt incidence on flue-cured tobacco. This study suggests B. amyloliquefaciens WS-10 as a novel biocontrol agent for sustainable agriculture due to its broad-spectrum antimicrobial activity and well colonization ability in the host plant.