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Bacillus velezensis LMY3-5 for the biocontrol of soft rot in kiwifruit: antifungal action and underlying mechanisms

Summary

Scientists discovered a beneficial bacteria called Bacillus velezensis that can effectively prevent soft rot disease in kiwifruit, which causes serious damage during storage. The bacteria works by producing natural antimicrobial compounds that damage the fungal pathogen’s cell walls and membranes, stopping it from growing. This biocontrol approach offers an environmentally friendly alternative to chemical fungicides, reducing pesticide residues while maintaining fruit quality and safety.

Background

Kiwifruit soft rot caused by Botryosphaeria dothidea is a serious fungal disease during storage that restricts the kiwifruit industry. Chemical antifungal agents are commonly used but can induce resistance and cause environmental pollution. Bacillus species are promising biocontrol agents that produce antimicrobial compounds including lipopeptides and enzymes.

Objective

To isolate and identify a bacterial strain with antifungal activity from kiwifruit tissues, characterize its antifungal properties against B. dothidea both in vitro and in vivo, elucidate the antifungal mechanisms, and detect the antimicrobial metabolites produced.

Results

LMY3-5 was identified as Bacillus velezensis and showed 97.32% suppression of B. dothidea spore germination and 73.59% inhibition of kiwifruit soft rot in vivo. SEM and TEM observations revealed severe mycelial damage with curved, wrinkled structures and compromised cell walls. PI staining and leakage assays confirmed cell membrane damage, while increased chitinase and β-1,3-glucanase activity indicated cell wall degradation. GC/LC-MS analysis identified 27 antimicrobial compounds including vanillin, nonanal, and dibutyl phthalate.

Conclusion

Bacillus velezensis LMY3-5 shows great potential as a biocontrol agent for kiwifruit soft rot through multiple antifungal mechanisms including cell membrane disruption, cell wall degradation, and production of diverse antimicrobial metabolites. This is the first report of B. velezensis with biocontrol properties isolated from kiwifruit endophytes, offering new possibilities for sustainable disease management.
  • Published in:Frontiers in Microbiology,
  • Study Type:Experimental Research,
  • Source: PMC12069402, PMID: 40365060
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