乳酸菌产苯乳酸对指状青霉的抑菌活性及作用机理

Antifungal Activity and Possible Mechanism of Action of Phenyllactic Acid Produced by Lactic Acid Bacteria against Penicillium digitatum

为探究乳酸菌Lactobacillus plantarum CKXP13和L.plantarum CWXP24产苯乳酸的能力以及苯乳酸对柑橘绿霉病的控制效果及其抑菌机理,本实验使用高效液相色谱法测定这两株乳酸菌的苯乳酸产量,并通过研究苯乳酸处理后指状青霉的孢子存活率、菌落直径、菌丝形态、胞外电导率来探究其抑菌机理,最后以柑橘果实绿霉病干预实验探究苯乳酸对绿霉病的控制效果。结果表明,L.plantarum CKXP13、L.plantarum CWXP24均能产生苯乳酸,产量分别为42.4 mg/L和91.9 mg/L,苯乳酸质量浓度为2.5、5.0、10.0 mg/mL条件下,指状青霉的孢子存活率、菌落直径随苯乳酸质量浓度上升而显著降低(P<0.05),菌丝也随苯乳酸质量浓度升高出现表面粗糙、相互缠绕、形成塌陷或树瘤状凸起的情况,同时乳酸菌还能增强病原菌细胞膜的通透性,促进细胞内容物泄漏,导致病原菌死亡。果实绿霉病干预实验证明,10、20 mg/mL苯乳酸都能有效控制柑橘果实绿霉病。综上所述,苯乳酸作为天然杀菌剂在控制柑橘采后绿霉病方面具有良好的应用潜力和开发前景。

This study was attempted to explore the ability of Lactobacillus plantarum CKXP13 and L.plantarum CWXP24 to produce phenyllactic acid(PLA),and the inhibitory effect and mechanism of action of PLA on citrus green mold.The phenyllactic acid-producing ability of L.plantarum was determined by high performance liquid chromatography(HPLC).The antifungal mechanism of action was explored by studying the spore survival rate,colony diameter,mycelial morphology,and extracellular electrical conductivity of P.digitatum after being treated with PLA.The results showed that both strains could produce PLA at yields of 42.4 and 91.9 mg/L,respectively.As the PLA concentration increased from 2.5 to 5.0 and 10.0 mg/mL,the spore viability and colony diameter of P.digitatum decreased significantly(P<0.05).Meanwhile,the hyphal surface appeared rough with dents or dendritic bulges on it and the hyphae were entangled.At the same time,PLA enhanced the permeability of the cell membrane of P.digitatum,promoted the leakage of cell contents,and caused the death of P.digitatum.PLA at concentrations of 10 and 20 mg/mL could effectively control citrus green mold.In conclusion,PLA has great potential for development and application as a natural fungicide in controlling postharvest green mold of citrus fruit.