Biotechnology Bulletin ›› 2025, Vol. 41 ›› Issue (10): 175-185.doi: 10.13560/j.cnki.biotech.bull.1985.2025-0264

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Screening, Identification and Optimization of Fermentation Conditions of Antagonistic Bacteria against Potato Early Blight

LYU Ji-min1(), LIU Wei1(), SUN Min1, LI Hong-shun2, PENG Zhen-xing2, QIU Peng-fei1, ZHU Qi-li1   

  1. 1.Linyi Agricultural R&D Center of Sinofert Co. , Ltd. , Linyi 276300
    2.Sinochem Agriculture(Linyi) R&D Center Co. , Ltd. , Linyi 276300
  • Received:2025-03-12 Online:2025-10-26 Published:2025-10-28
  • Contact: LIU Wei E-mail:jimin.lv@syngentagroup.cn;wei.liu-4@syngentagroup.cn

Abstract:

Objective Potato early blight, caused by Alternaria solani, is a global crop disease that severely threatens potato yield and quality. This study is aimed to isolate strains with strong inhibitory effects against A. solani from potato rhizosphere soil and optimize their fermentation conditions, providing a microbial resource for developing biocontrol agents against potato early blight. Method Antagonistic strains against A. solani were screened using gradient dilution and plate confrontation methods. The strains were identified through morphological observation, API 50CH physiological-biochemical tests, 16S rRNA gene sequencing, and gyrB gene sequencing. Single-factor and orthogonal experiments were conducted to optimize the fermentation conditions of the antagonistic strains. Result Six antagonistic strains against A. solani were isolated, and strain LYB08 showing the highest fungistatic rate 54.10%. Strain LYB08 was identified as Bacillus velezensis. After optimization, the optimal carbon and nitrogen sources for fermentation were corn starch and soybean meal. When fermented with corn starch 30 g/L, soybean meal 20 g/L, and initial pH 7.5, the viable spore number reached 1.17×1010 CFU/mL, total number of viable bacteria was 1.32×1010 CFU/mL, representing increases of 120.75% and 116.39% respectively, compared to the initial medium. When fermented with corn starch 30 g/L, soybean meal 30 g/L, and initial pH 8.5, the fungistatic rate of the fermentation broth peaked at 81.04%, a 50.49% improvement over the initial medium. Conclusion An antagonistic strain LYB08 is successfully isolated against potato early blight, which may provide a basis for the development of biocontrol agents for this disease.

Key words: biocontrol agent, potato early blight, screening and identification, fermentation conditions, Bacillus velezensis