柠檬醛和辛醛混合物对指状青霉的抑制作用

Inhibitory Effects of Citral and Octanal Mixture on Penicillium digitatum

摘要:

本研究采用琼脂稀释培养法测定柠檬醛、辛醛以及柠檬醛+辛醛混合物（V/V，4:1）对指状青霉菌丝体生长的影响，并对柠檬醛+辛醛混合物抑菌机制进行初步探讨。结果表明，柠檬醛+辛醛混合物（V/V，4:1）能明显抑制指状青霉菌丝体生长，最小抑菌浓度（minimal inhibitory concentration，MIC）和最小杀菌浓度（minimal fungicidal concentration，MFC）均为2.50 μL/mL，而柠檬醛的MIC和MFC分别为2.50 μL/mL和5.00 μL/mL，辛醛的MIC和MFC分别为0.63 μL/mL和2.50 μL/mL。扫描电镜结果显示，经MIC（MFC）的柠檬醛+辛醛混合物处理后，指状青霉菌丝体表面发生严重塌陷和多重褶皱，菌丝结构发生不规则扭曲，表明细胞完整性遭到严重破坏。此外，指状青霉菌丝体胞外pH、胞外电导率以及260 nm处的吸光度值均随柠檬醛+辛醛混合物（V/V，4:1）浓度增加显著增加。本研究结果表明，柠檬醛+辛醛混合物（V/V，4:1）能破坏指状青霉细胞结构的完整性，增加细胞膜通透性，导致细胞内物质泄漏，从而导致菌丝体死亡。

Abstract:

The effects of citral, octanal, and citral/octanal mixture (4:1, V/V) on the mycelial growth of Penicillium digitatum were investigated by using the agar dilution method. In addition, preliminary investigation was performed on the corresponding inhibitory mechanism of citral/octanal mixture against P. digitatum. Results showed that the citral/octanal mixture significantly inhibited mycelial growth of P. digitatum, with a minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of 2.50 μL/mL for both. In contrast, the MIC and MFC of citral were 2.50 and 5.00 μL/mL, respectively, and those of octanal were 0.63 and 2.50 μL/mL, respectively. Scanning electron microscopy (SEM) showed that citral/octanal mixture treatment resulted in severe collapse and multiple folds on the hypha surface, causing irregular distortions in the structure and destroying cell integrity. Moreover, extracellular pH, extracellular conductivity, and absorbance at 260 nm significantly increased after treatment with citral/octanal (4:1, V/V). These results indicated that the citral/octanal mixture could destroy cellular integrity and increase the cell membrane permeability of P. digitatum, thereby causing leakage of cellular components, leading to the death of P. digitatum.