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Chinese Journal Of Biological Control ›› 2019, Vol. 35 ›› Issue (6): 930-939.DOI: 10.16409/j.cnki.2095-039x.2019.06.021

• RESEARCH REPORTS • Previous Articles     Next Articles

Optimization of Culture Conditions for Antifungal Substances Produced by Bacillus subtilis M29 and Preliminary Study on the Composition of Antifungal Substances

JI Guanning1,2, WANG Zhipeng1, JIAO Jiaguo1, HU Feng1, LI Huixin1,2   

  1. 1. College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China;
    2. Jiangsu Collaborative Innovation Center for Solid Organic Waste Utilization, Nanjing 210095, China
  • Received:2019-03-26 Online:2019-12-08 Published:2019-12-18

Abstract: Our previous work found that Bacillus subtilis M29 has a good control effect on cucumber Fusarium wilt. However, the composition and mechanism of its antifungal substances are still unclear. Here, we will screen the optimal culture conditions of this strain, and determine the composition of antifungal substances produced by the strain. We determined the culture conditions based on the antifungal effect of the substances, optimal conditions (e.g., temperature and pH) were selected when the stain displayed the strongest antifungal effect. Then, we analyzed the composition of antifungal substances using heat treatment, enzyme treatment, gene detection and mass spectrometry. The results showed that the antifungal effect of the antifungal substances produced by strain M29 was strongest when Landy-based medium was used with an initial pH of 7, a culture temperature of 30℃ and a culture time of 36-48 h. The crude extract of the antimicrobial substance still had antifungal activity after heat treatment and enzyme treatment. In addition, we amplified the synthetic gene fenB of fengycin from the genome DNA of strain M29 and detected the molecular weight of fengycin B by mass spectrometry. Therefore, we speculate that the lipopeptide antibiotic fengycin B may be present in the secretions of strain M29. We concluded that Bacillus subtilis M29 may inhibit the growth of pathogenic fungal by secreting lipopeptide antibiotics, and the antifungal ability can be significantly improved by optimizing the culture conditions. This study will not only contribute to a better understanding of the antimicrobial mechanism of the strain, but also provide theoretical guidance for the practical application of this strain in the future.

Key words: Bacillus subtilis M29, culture conditions, antifungal substances, lipopeptide compounds

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