Biocontrol Potential of Bacillus stercoris Strain DXQ-1 Against Rice Blast Fungus Guy11

TL;DR

A soil bacterium, Bacillus stercoris DXQ-1, shows strong potential as a natural alternative to chemical fungicides for controlling rice blast disease.

Contribution

The study identifies and characterizes a novel Bacillus stercoris strain with potent antifungal activity and biocontrol potential against rice blast.

Findings

DXQ-1 disrupts fungal hyphae and inhibits conidial germination, reducing germination to 83.33%.

Optimized fermentation conditions produced a broth with >90% inhibition against M. oryzae and N. oryzae.

Field trials showed DXQ-1 significantly promotes rice growth and controls disease effectively.

Abstract

Fungal diseases severely threaten global agriculture, while conventional chemical fungicides face increasing restrictions due to environmental and safety concerns. In this study, we isolated a soil-derived Bacillus stercoris strain, DXQ-1, exhibiting strong antagonistic activity against plant pathogenic fungi, notably Magnaporthe oryzae, the causal agent of rice blast. Scanning electron microscopy revealed that DXQ-1 disrupts fungal hyphae and inhibits conidial germination, with a 24 h crude broth treatment reducing germination to 83.33% and completely blocking appressoria formation. LC-MS-based metabolomic analysis identified key antifungal components, including lipids (35.83%), organic acid derivatives (22.15%), and small bioactive molecules (e.g., Leu-Pro, LPE 15:0). After optimizing fermentation conditions (LB medium, pH 7.0, 28 °C, 48 h), the broth showed >90% inhibition against M. oryzae and Nigrospora oryzae and retained high thermal (68 °C, 1 h) and UV (4 h) stability. Field trials demonstrated effective disease control and significant promotion of rice growth, increasing plant height (17.7%), fresh weight (53.3%), and dry weight (33.3%). These findings highlight DXQ-1 as a promising biocontrol agent, offering a sustainable and effective alternative for managing fungal diseases in crops.

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