Isolation and yield optimization of lipopeptides from Bacillus subtilis Z‐14 active against wheat take‐all caused by Gaeumannomyces graminis var. tritici
2021
Zhang, Xuechao | Chen, Xiaomeng | Qiao, Xinlei | Fan, Xuerui | Huo, Xiaoyi | Zhang, Dongdong
Wheat take‐all, caused by the soil‐borne fungus Gaeumannomyces graminis var. tritici, is one of the major constraints on wheat production worldwide. Bacillus subtilis Z‐14 exerts significant biocontrol activity against wheat take‐all, and lipopeptide antibiotics are the main antifungal substances. Herein, lipopeptide antibiotics C14–C15 iturin A, C14–C16 fengycin A, and C15–C17 fengycin B from B. subtilis Z‐14 culture filtrates were separated and identified by high‐performance liquid chromatography, matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry, and mass spectrometry/mass spectrometry, respectively. The optimal medium components for Z‐14 lipopeptide antibiotic production were 3.85 g/L corn flour, 1.57 g/L soybean meal, 0.03 g/L FeSO₄·7H₂O, 0.2 g/L NaH₂PO₄·2H₂O, and 0.4 g/L Na₂HPO₄·2H₂O. Quantification analysis by high‐performance liquid chromatography showed that fengycins played a main role in antifungal activity against Gaeumannomyces graminis var. tritici. Quantitative reverse transcription polymerase chain reaction showed that lipopeptide synthesis genes fenD and ituC reached maximum expression levels after 48 h of fermentation. The strongest control of wheat take‐all by Z‐14 was achieved by adding 30 mL of culture filtrate per 350 g of soil in pot experiments, during which disease reduction reached 88.15%. This study provides theoretical support and a material basis for the prevention and treatment of wheat take‐all disease.
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