柠檬皮中柠檬苦素对黑曲霉的抑菌特性和机理

本研究以柠檬皮中柠檬苦素为原料，对其抑制黑曲霉的抑菌活性、抑菌活性的稳定性和抑菌机理进行了研究。结果表明：柠檬皮中柠檬苦素对黑曲霉的最小抑菌浓度（MIC）和最小杀菌浓度（MFC）分别为625 μg/mL、5000 μg/mL；对孢子萌发和菌丝生长抑制的半最大效应浓度（EC50）分别为311.03 μg/mL和291.63 μg/mL。柠檬苦素对黑曲霉的抑菌活性在紫外光照下受到抑制；在pH值为6~7时受到抑制；金属离子Fe3+、Fe2+可增强其抑菌活性。在柠檬皮中柠檬苦素作用下，黑曲霉的胞外碱性磷酸酶（AKP）活力、可溶性蛋白和菌丝体总糖含量发生很大变化；扫描电子显微镜观察发现黑曲霉孢子发生了变形、破裂、溶出物附着的现象。因此，柠檬苦素破坏了黑曲霉细胞壁和细胞膜的完整性，造成大量内容物渗出，影响了细胞正常代谢，进而抑制了菌体细胞的生长繁殖。
The antifungal activity, stability and mechanism of limonin from lemon peel against Aspergillus niger were investigated. The results showed that the minimal inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) of limonin from lemon peel on Aspergillus Niger were 625 μg/mL and 5000 μg/mL respectively, and the half-effective concentration (EC50) on spore germination and mycelium growth were 311.03 μg/mL and 291.63 μg/mL respectively. The antifungal activity of limonin on Aspergillus niger was weakened under UV light and pH 6~7. Fe3+ and Fe2+ could enhance the antifungal activity. The limonin from lemon peel could greatly change extracellular alkaline phosphatase (AKP) activity, soluble protein and total sugar content of mycelium of Aspergillus niger. Therefore, limonin destroyed the integrity of cell wall and cell membrane of Aspergillus niger, resulting in a large amount of content exudation, affecting the normal metabolism of cells, thereby inhibiting the growth and reproduction of cells.