Antifungal Effect and Mechanism of Bacillus velezensis LY7 on Colletotrichum scovillei

doi:10.16409/j.cnki.2095-039x.2025.02.044

Abstract

Abstract: Pepper anthracnose is one of the three major diseases of pepper. Due to the genetic diversity of Colletotrichum pathogen complexes, single-site fungicides are difficult to achieve good control effects. This study explored its biological control methods in order to provide more effective measures for the prevention and control of pepper anthracnose. A strain of Bacillus velezensis LY7 with good inhibitory effect on Colletotrichum scovillei was isolated from pepper leaves. Its biological characteristics were determined by colorimetry, and the optimal fermentation conditions were optimized by growth rate method. The volatiles of the strain LY7 were identified by solid phase microextraction gas chromatography-mass spectrometry (SPME?GC?MS) and assessed for virulence. In addition, the antifungal lipopeptide was isolated and purified by hydrochloric acid precipitation method, and identified by liquid chromatography-mass spectrometry (LC-MS). Further, the antifungal active substances produced by strain LY7 were isolated and identified, and the control effect was determined by field experiment. The results showed that the growth conditions of strain LY7 could meet its application in field production practice. The optimal fermentation conditions were as follows: YSP medium with glucose as carbon source, yeast powder and peptone as nitrogen source, 1% (v/v) inoculation, 30 ℃, pH 5.0, 160 r/min for 72 h, and the stability of its metabolites was better. Strain LY7 could produce 6 volatile substances, including 2-undecanol, 2-undecanone and 2-dodecanone, among which 2-undecanol has higher toxicity to C. scovillei with an EC₅₀ of 6.73 μL/mL. In addition, strain LY7 can also produce 56 potential antibacterial lipopeptides that inhibit the occurrence of C. scovillei, including 42 fatty amides (FA), 8 isoamyl alcohol lipids (PR), 3 sphingosines (SP), 2 glycerophospholipids (GP), and 1 quaternary ammonium alkali (QA). Field experiments showed that the 80-fold diluted fermentation broth of strain LY7 had the highest control effect, reaching 76.70%, which was significantly higher than the treatment of prochloraz in the field. The results of this study laid a foundation for the future development and application of the strain.

Key words: pepper anthracnose, Bacillus velezensis, volatile substances, antibacterial lipopeptide, field control effect

CLC Number:

S476

Lü Hong, ZOU Xiaolu, XU Zilu, QIN Nan, YIN Hui, REN Lu, ZHAO Xiaojun. Antifungal Effect and Mechanism of Bacillus velezensis LY7 on Colletotrichum scovillei[J]. Chinese Journal of Biological Control, 2025, 41(5): 1104-1118.

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