Genome analysis and exploration of Bacillus subtilis XH-10, a potential biocontrol strain

Wheat is an important staple crop that has received widespread attention in recent years. Fusarium head blight (FHB) seriously affects wheat yield and quality, and also causes mycotoxin contamination.

To explore green control strategies, this study focused on the mining of biocontrol resources against FHB.

A bacterial strain, XH-10, showing strong antagonistic activity against Fusarium graminearum (the major causal agent of FHB), was isolated using the dilution plating method and dual culture assay. Based on morphological characteristics and 16S rDNA gene sequence analysis, strain XH-10 was identiffed as Bacillus subtilis. Antimicrobial tests using the fermentation broth showed that the growth of the pathogen was inhibited in the presence of the XH-10 fermentation broth, accompanied by hyphal malformation, swelling, breakage, and a signiffcant reduction in spore production. Pathogenicity assays revealed that the addition of the XH-10 fermentation broth reduced the virulence of the F. graminearum PH-1 toward wheat. Whole-genome analysis showed that the genome size of strain XH-10 is 4.1 Mb, with a GC content of 43.78%, encoding 4,233 genes. Seven secondary metabolite biosynthetic gene clusters (BGCs) were predicted, including those responsible for the synthesis of known antimicrobial substances such as surfactin, bacillaene, fengycin, bacillibactin, subtilosin A, and bacilysin. Functional annotation further revealed the presence of siderophore biosynthesis gene clusters, glycoside hydrolase genes including chitinase, and sporulation-related genes.

The XH-10 exhibits promising biocontrol potential against wheat FHB, and its biocontrol mechanisms may involve the production of multiple antimicrobial compounds and the secretion of cell wall-degrading enzymes. This study provides a valuable microbial resource and theoretical basis for the development of biocontrol agents against wheat FHB.