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Characterization of Two Potential Biocontrol Bacillus Strains Against Maize Stalk Rot

Summary

Scientists discovered two beneficial bacteria, Bacillus subtilis and Bacillus siamensis, that can protect maize plants from a serious fungal disease called stalk rot. These bacteria work in two ways: they directly kill the fungus and they promote healthy plant growth. By analyzing the bacteria’s genetic makeup, researchers found that they produce multiple natural antibiotic compounds that explain their powerful disease-fighting abilities. This research suggests these bacteria could be used as a natural, environmentally-friendly alternative to chemical fungicides for protecting crops.

Background

Maize stalk rot (MSR) is a devastating fungal disease caused primarily by Fusarium graminearum, resulting in significant yield losses worldwide. Biological control agents, particularly Bacillus strains, have emerged as environmentally friendly alternatives to chemical fungicides for managing MSR and other Fusarium diseases.

Objective

To isolate and characterize two Bacillus strains from apple rhizosphere soil with potential biocontrol activity against F. graminearum, evaluate their plant-growth-promoting properties, and elucidate their antimicrobial mechanisms through whole-genome sequencing.

Results

B. subtilis KP3P9 and B. siamensis K13C inhibited F. graminearum growth by 71.58% and 73.4% respectively in vitro. Both strains significantly promoted maize seedling growth and reduced disease severity indices in infected seedlings. Genome analysis revealed 14 biosynthetic gene clusters in each strain encoding antimicrobial compounds including fengycin, bacillibactin, subtilin, and bacilysin. Both strains demonstrated broad-spectrum activity against other Fusarium pathogens with inhibition rates exceeding 70%.

Conclusion

B. subtilis KP3P9 and B. siamensis K13C are promising biocontrol agents for maize stalk rot and other Fusarium diseases, combining plant-growth-promotion with strong antifungal activity mediated by multiple secondary metabolites. Field experiments are warranted to validate their efficacy, and further transcriptomic and metabolomic analyses are recommended to identify key genes and metabolites driving their biocontrol mechanisms.
  • Published in:Microorganisms,
  • Study Type:Laboratory and Pot Experiment Study,
  • Source: PMID: 41156715, DOI: 10.3390/microorganisms13102255
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