紫苏醛对杨梅主要致病菌桔青霉的抑菌活性及作用机制

Antifungal Activity and Mechanism of Perillaldehyde against Penicillium citrinum,a Major Fungal Pathogen of Myrica rubra

紫苏醛是从紫苏叶中提取出来的一种绿色安全的天然抑菌物质,同时也被作为食品添加剂应用到食品生产中。本研究通过最小抑菌浓度、孢子萌发率和菌丝生长抑制实验探究了紫苏醛对杨梅主要致病菌桔青霉的抑菌效果,并通过研究桔青霉菌丝形态和超微结构、细胞膜损伤机制、膜脂过氧化情况以及官能团变化,探讨桔青霉的抑菌机理。结果表明:紫苏醛对桔青霉的最小抑菌浓度为120μL/L;经过120μL/L紫苏醛处理后菌丝生长得到完全抑制,相对电导率、丙二醛含量上升,与未处理组相比,经过90μL/L紫苏醛处理的桔青霉中麦角固醇、总脂质、几丁质水平和线粒体ATP酶活力分别下降了80.00%、81.25%、64.97%和87.40%,破坏了桔青霉细胞膜的通透性,影响细胞膜正常生理功能;扫描电子显微镜和透射电子显微镜观察发现,紫苏醛处理后的桔青霉头部扫帚状分生孢子头消失,菌丝出现断裂、消融等现象,同时细胞膜遭到破坏,内容物外泄,细胞内部发生皱缩。与0 h相比,处理5 h时120μL/L紫苏醛处理组的桔青霉中可溶性蛋白、可溶性糖和核酸泄漏量分别增加了71.20%、210.93%和117.31%,验证了细胞膜损伤情况;通过傅里叶变换红外光谱发现,紫苏醛处理的桔青霉羟基、甲基、芳香族碳骨架、苯环碳骨架等官能团含量下降,内部物质被逐渐消耗。综上,紫苏醛对杨梅主要致病菌桔青霉具有良好的抑菌效果,通过破坏细胞膜结构、改变膜通透性、干扰能量代谢及破坏蛋白质和遗传物质等途径发挥抑菌作用,可作为天然保鲜剂具有一定研究和开发前景。

Perillaldehyde is a green and safe natural antibacterial substance extracted from perilla leaves,which is also used as a food additive in food production.In this study,the inhibitory effect of perillaldehyde on Penicillium citrinum,a major pathogen of Chinese bayberry(Myrica rubra),was investigated by minimum inhibitory concentration(MIC),spore germination rate and mycelial growth inhibition assays,and the underlying mechanism was elucidated by studying the mycelial morphology and ultrastructure,cell membrane damage,membrane lipid peroxidation and changes in functional groups.The results showed that the MIC of perillaldehyde on P.citrinum was 120μL/L.Mycelial growth was completely inhibited by treatment with 120μL/L perillaldehyde,and the relative conductivity and malondialdehyde(MDA)content increased.Compared with the untreated group,ergosterol,total lipid and chitin contents and mitochondrial adenosine triphosphatase(ATPase)activity decreased by 80.00%,81.25%,64.97%and 87.40%in P.citrinum treated with 90μL/L perillaldehyde.The treatment with perillaldehyde damaged cell membrane permeability and affected the normal physiological function of the cell membrane.By scanning electron microscopy(SEM)and transmission electron microscopy(TEM),it was found showed that the broom-like conidial head of P.citrinum disappeared after perillaldehyde treatment,and the mycelia appeared to be broken and ablated.Moreover,the cell membrane was broken,intracellular contents leaked out,and the cells became shriveled.In addition,the amounts of leakage of soluble protein,soluble sugar and nucleic acid from P.citrinum treated with 120μL/L perillaldehyde for 5 h increased by 71.20%,210.93%and 117.31%compared with those before the treatment,which verified cell membrane damage.By using Fourier transform infrared(FTIR)spectroscopy,it was found that the contents of functional groups such as hydroxyl,methyl,aromatic carbon skeleton and benzene ring carbon skeleton in perillaldehyde treated P.citrinum decreased,and internal substances were gradually consumed.In summary,perillaldehyde showed a good antifungal activity on P.citrinum by destroying cell membrane structure,changing membrane permeability,interfering with energy metabolism and destroying protein and genetic material.Perillaldehyde has good research and development prospects as a natural preservative.