Department of Biology, College of Life Science and Agroforestry, Qiqihar University, Qiqihar 161006, China.
Heilongjiang Provincial Technology Innovation Center of Agromicrobial Preparation Industrialization, Qiqihar 161006, China.
FEMS Microbiol Ecol. 2022 Jul 21;98(8). doi: 10.1093/femsec/fiac080.
In this study, the antifungal mechanism of secondary metabolites from the WB strain against Fusarium oxysporum f. sp. niveum (Fon) was investigated. The WB strain induced the accumulation of reactive oxygen species in Fon hyphae and caused morphological changes, including surface subsidence and shrinkage deformation. The cell-free supernatants (CFSs) from WB treatment caused a significant increase in superoxide dismutase, catalase, peroxidase and glutathione reductase activities and the contents of soluble protein and malondialdehyde. Additionally, CFSs from WB decreased the fusaric acid concentration in Fon. Transcriptome analysis revealed that the expression of some antioxidant-related genes was upregulated and that the expression of mycotoxin-related genes was downregulated. Four polypeptide compounds from the WB strain, including iturin A, fengycin, surfactin and bacitracin, were identified by ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis and complete genome mining. RT-qPCR and a quantitative analysis confirmed that the presence of Fon induced the expression of polypeptide genes and elevated polypeptide production. The combined minimum inhibitory concentration and quantitative analysis of four polypeptides revealed that iturin A, fengycin, surfactin and bacitracin might be responsible for inhibiting the growth of Fon. In conclusion, secondary metabolites from strain WB exhibited antifungal effects on Fon by triggering oxidative stress and decreasing toxin levels.
在这项研究中，研究了 WB 菌株的次生代谢产物对尖孢镰刀菌（Fon）的抗真菌机制。WB 菌株诱导 Fon 菌丝中活性氧的积累，并导致形态变化，包括表面凹陷和收缩变形。WB 处理的无细胞上清液（CFS）导致超氧化物歧化酶、过氧化氢酶、过氧化物酶和谷胱甘肽还原酶活性以及可溶性蛋白和丙二醛含量显著增加。此外，WB 的 CFS 降低了 Fon 中的 Fusaric 酸浓度。转录组分析显示，一些抗氧化相关基因的表达上调，而真菌毒素相关基因的表达下调。通过超高效液相色谱-电喷雾电离串联质谱分析和全基因组挖掘，从 WB 菌株中鉴定出四种多肽化合物，包括伊枯草菌素 A、丰原素、表面活性剂和杆菌肽。RT-qPCR 和定量分析证实，Fon 的存在诱导了多肽基因的表达并提高了多肽的产生。四种多肽的最低抑菌浓度和定量分析表明，伊枯草菌素 A、丰原素、表面活性剂和杆菌肽可能负责抑制 Fon 的生长。总之，WB 菌株的次生代谢产物通过触发氧化应激和降低毒素水平对 Fon 表现出抗真菌作用。
