Guizhou Vocational College of Agriculture, Qingzhen 551400, China.
Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
Molecules. 2024 Oct 13;29(20):4850. doi: 10.3390/molecules29204850.
Taking the endophytic fungus UJ3-2, isolated from , as the experimental material, this study aimed to explore the composition of its metabolites and the underlying mechanisms by which it inhibits . Initially, the MIC, MBC, inhibitory curves, biofilm growth, and extracellular nucleic acids and proteins of S. aureus in response to the metabolites were measured. Secondly, PI staining and SEM were used to evaluate the impact of the metabolites on the integrity of the cell wall and overall morphology of . Additionally, UPLC-MS was employed to analyze the composition of the secondary metabolites. The UJ3-2 strain was identified as based on ITS sequencing and designated as UJ3-2. Our results revealed that the metabolites of UJ3-2 exhibited excellent in vitro antibacterial activity against , with both MIC and MBC values of 3.125 mg/mL. The inhibitory curve confirmed that 1 MIC of UJ3-2 metabolites could completely inhibit the growth of within 24 h. With increasing concentrations of UJ3-2 metabolites, the growth of biofilms was significantly suppressed, and obvious leakage of nucleic acids and proteins was observed. PI fluorescence staining indicated that various concentrations of UJ3-2 metabolites disrupted the integrity of the cell membrane. SEM observation revealed that the treated surfaces became rough, and the bacteria shrank and adhered to each other, showing a dose-dependent effect. UPLC-MS analysis suggested that the main components of the fermented metabolites were 6-oxocineole (17.92%), (S)-2-acetolactate (9.91%), 3-methyl-cis,cis-muconate (4.36%), and 8-oxogeranial (3.17%). This study demonstrates that the endophytic fungus UJ3-2 exhibits remarkable in vitro antibacterial effects against , primarily by enhancing the permeability of the cell membrane, causing the leakage of its intracellular contents, and altering the bacterial surface morphology to inhibit the pathogen. The endophytic fungus UJ3-2 has a good antibacterial effect on , which gives it certain application prospects in the screening and industrial production of new and efficient natural antibacterial active substances.
以分离自 的内生真菌 UJ3-2 为实验材料，本研究旨在探索其代谢产物的组成及其抑制 机制。首先，测定了代谢产物对 的 MIC、MBC、抑制曲线、生物膜生长以及金黄色葡萄球菌胞外核酸和蛋白质的影响。其次，通过 PI 染色和 SEM 评估代谢产物对 细胞壁完整性和整体形态的影响。此外，还采用 UPLC-MS 分析了次生代谢产物的组成。根据 ITS 测序鉴定 UJ3-2 菌株为 ，并命名为 UJ3-2。结果表明，UJ3-2 代谢产物对 具有良好的体外抗菌活性，MIC 和 MBC 值均为 3.125 mg/mL。抑制曲线证实，1 MIC 的 UJ3-2 代谢产物可在 24 h 内完全抑制 的生长。随着 UJ3-2 代谢产物浓度的增加， 生物膜的生长受到明显抑制，且观察到核酸和蛋白质明显泄漏。PI 荧光染色表明，不同浓度的 UJ3-2 代谢产物破坏了 细胞膜的完整性。SEM 观察显示，处理后的 表面变得粗糙，细菌收缩并相互粘连，呈现出剂量依赖性。UPLC-MS 分析表明，发酵代谢产物的主要成分有 6-氧诺草酮（17.92%）、（S）-2-乙酰乳酸（9.91%）、3-甲基顺式，顺式-粘康酸（4.36%）和 8-氧姜烯醛（3.17%）。本研究表明，内生真菌 UJ3-2 对 具有显著的体外抗菌作用，主要通过增强 细胞膜的通透性，导致其细胞内内容物泄漏，并改变细菌表面形态来抑制病原体。内生真菌 UJ3-2 对 具有良好的抗菌作用，这为其在新型高效天然抗菌活性物质的筛选和工业生产中提供了一定的应用前景。
