Integrating biocontrol efficacy and genomic potential of Bacillus velezensis BJ-1141: from broad-spectrum antagonism to tomato Fusarium wilt suppression.

Aims

To isolate and characterize a rhizosphere-derived Bacillus velezensis strain with biocontrol and plant growth-promoting potential, and to evaluate its efficacy against plant pathogens together with its genomic basis.

Methods

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Results

A bacterial strain (BJ-1141) was isolated from the rhizosphere and identified as B. velezensis based on morphological characteristics and phylogenetic analyses of 16S rRNA and gyrA gene sequences. The strain exhibited broad-spectrum antagonistic activity against 24 plant pathogenic fungi, inhibiting 23 pathogens by more than 50%, with a maximum inhibition rate of 95.57%. BJ-1141 produced hydrolytic enzymes (amylase, protease, cellulase and pectinase) and plant growth-promoting factors, including siderophores and indole-3-acetic acid (IAA). It also demonstrated phosphorus solubilization, nitrogen fixation and biofilm formation. Greenhouse experiments showed that root application of BJ-1141 effectively controlled tomato Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici, achieving control efficacies of 81.13 - 85.93%, which were higher than those of chemical and commercial microbial treatments. In addition, BJ-1141 significantly increased plant height, biomass and chlorophyll content in tomato and lettuce seedlings. Whole-genome sequencing revealed a 3 902 965 bp genome containing 13 biosynthetic gene clusters associated with antimicrobial secondary metabolites, including surfactin, fengycin, bacillaene, difficidin, macrolactin H, bacillibactin and bacilysin.

Conclusions

B. velezensis BJ-1141 is a multifunctional bacterial strain with strong biocontrol efficacy and plant growth-promoting traits, supported by genomic evidence, and represents a promising candidate for sustainable crop disease management.