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<p>In this study, the pathogenicity of the fungi <i>Fusarium</i> spp., <i>Alternaria</i> spp., and <i>Colletotrichum coccodes</i> isolated from diseased tissues of potato tubers was evaluated. Most strains caused disease spots and rot in potato tubers and were identified as the primary pathogens responsible for fungal diseases during potato storage. Concurrently, four antagonistic bacterial strains were screened using the plate confrontation and Oxford cup methods. These strains exhibited varying degrees of antifungal activity, among which strain 1-2-2-BJK demonstrated the strongest antagonistic activity. Based on its morphological, physiological, and biochemical characteristics, as well as 16S rDNA sequence analysis, strain 1-2-2-BJK was identified as <i>Bacillus velezensis</i>. The antagonistic mechanism of this strain against <i>Fusarium tricinctum</i> was further investigated, and electron microscopy revealed that fungal hyphae inhibited by antagonistic bacteria exhibited various forms of structural damage. Additionally, 1-2-2-BJK was found to possess lipopeptide synthesis genes encoding antibiotic compounds, such as fengycin, bacilysin, iturin A, and surfactin. The lipopeptides were extracted, and their antifungal activity against <i>F. tricinctum</i> was assessed via two independent bioassays. The extract showed significant inhibitory effects against the potato pathogen, with a minimum inhibitory concentration (MIC) of 0.049&#xa0;mg/mL determined by the agar diffusion method and a half-maximal effective concentration (EC₅₀) of 105.59&#xa0;µg/mL determined by the mycelial growth rate method.&#xa0;Furthermore, the antagonistic bacterium produced hydrolases capable of degrading fungal cell walls, and its inoculation significantly enhanced the activity of defense-related enzymes in potatoes. The strain 1-2-2-BJK shows considerable biocontrol potential against potato fungal pathogens and may provide a theoretical foundation and technical basis for the biological control of potato diseases and the development of biocontrol bacterial resources.</p>

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Screening of Antagonistic Bacteria against Potato Fungal Diseases and their Biological Control Mechanisms during Potato Storage

  • 期刊论文

  • 发表日期：

    2026年6月26日

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  • Tianyan Xie,
  • Haojie Zhang,
  • Huifang Wu,
  • Wei Li,
  • Jian Wang,
  • Shuo Shen

摘要

In this study, the pathogenicity of the fungi Fusarium spp., Alternaria spp., and Colletotrichum coccodes isolated from diseased tissues of potato tubers was evaluated. Most strains caused disease spots and rot in potato tubers and were identified as the primary pathogens responsible for fungal diseases during potato storage. Concurrently, four antagonistic bacterial strains were screened using the plate confrontation and Oxford cup methods. These strains exhibited varying degrees of antifungal activity, among which strain 1-2-2-BJK demonstrated the strongest antagonistic activity. Based on its morphological, physiological, and biochemical characteristics, as well as 16S rDNA sequence analysis, strain 1-2-2-BJK was identified as Bacillus velezensis. The antagonistic mechanism of this strain against Fusarium tricinctum was further investigated, and electron microscopy revealed that fungal hyphae inhibited by antagonistic bacteria exhibited various forms of structural damage. Additionally, 1-2-2-BJK was found to possess lipopeptide synthesis genes encoding antibiotic compounds, such as fengycin, bacilysin, iturin A, and surfactin. The lipopeptides were extracted, and their antifungal activity against F. tricinctum was assessed via two independent bioassays. The extract showed significant inhibitory effects against the potato pathogen, with a minimum inhibitory concentration (MIC) of 0.049 mg/mL determined by the agar diffusion method and a half-maximal effective concentration (EC₅₀) of 105.59 µg/mL determined by the mycelial growth rate method. Furthermore, the antagonistic bacterium produced hydrolases capable of degrading fungal cell walls, and its inoculation significantly enhanced the activity of defense-related enzymes in potatoes. The strain 1-2-2-BJK shows considerable biocontrol potential against potato fungal pathogens and may provide a theoretical foundation and technical basis for the biological control of potato diseases and the development of biocontrol bacterial resources.