Bacillus amyloliquefaciens A-1 inhibiting fungal spoilage in agricultural products is improved by metabolic engineering of enhancing surfactin yield

文献类型： 外文期刊

第一作者： Hu, Yafan

作者： Hu, Yafan;Yang, Xu;Tai, Bowen;Wang, Gang;Xing, Fuguo;Zhang, Xinlong;Yin, Yixuan

作者机构：

关键词： Bacillus amyloliquefaciens; Aspergillus flavus; Aspergillus westerdijkiae; Antifungal mechanism; Surfactin; Agricultural products

期刊名称：FOOD RESEARCH INTERNATIONAL （ 影响因子：8.1； 五年影响因子：7.7 ）

ISSN： 0963-9969

年卷期： 2024 年 175 卷

页码：

收录情况： SCI

摘要： Fungi and subsequent mycotoxins contamination in agricultural products have caused enormous losses and great harm to human and animal health. Biological control has attracted the attention of researchers due to its advantages, including mild conditions, low cost, high efficiency and low nutrient loss. In this study, a newly isolated strain Bacillus amyloliquefaciens A-1 (A-1), was screened for its ability to inhibit the growth and Aflatoxin B1 (AFB1) production of Aspergillus flavus NRRL 3357. Electron microscopy results revealed that mycelium and conidia of A. flavus were destroyed by A-1, affecting hyphae, cell walls, cell membranes and organelles. RNA-seq analysis indicated disturbance in gene expression profiles of A. flavus, including amino acid degradation and starch and sucrose metabolism pathways. Importantly, the biosynthesis of AFB1 was significantly inhibited by the down-regulation of key regulatory genes, aflR and aflS, and the simultaneous down-regulation of most structural genes. Genome analysis predicted six secondary metabolites biosynthetic gene clusters. Then, four surfactin synthesized by cluster C were identified as the main active substance of A-1 using HPLC-Q-TOF-MS. The addition of alanine, threonine, Fe2+ increased surfactin production. Notably, the overexpression of comX also improved surfactin production. The vivo test results indicated that A-1 could significantly inhibit the decay of pear by Aspergillus westerdijkiae, and the mildew of maize and peanuts. Especially, the overexpression of comX in A-1 could enhance the inhibitory activity. In conclusion, the inhibition mechanism of A-1 was revealed, and comX was found can improve the production of surfactin and subsequent activities, which provides the scientific basis for the development of biocontrol agents to reduce spoilage in agricultural products.

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