植物乳杆菌LNL2-4-2对互隔交链孢霉的抑制作用

Inhibition Effect of Lactobacillus plantarum LNL2-4-2 on Alternaria alternata

互隔交链孢霉是导致果蔬采后黑斑病的主要病原体。本文采用菌饼法从发酵蔬菜来源的乳酸菌中筛选对互隔交链孢霉有拮抗作用的菌株,利用生理生化及16S rDNA测序鉴定乳酸菌。并进一步观察霉菌孢子超微结构的变化,通过测定霉菌孢子的电导率、丙二醛、可溶性蛋白质及可溶性糖含量的变化,初步探究乳酸菌对互隔交链孢霉的抑制机理。结果表明:植物乳杆菌LNL2-4-2对互隔交链孢霉的抑制率为80.86%,作用最强。采用10^(9) CFU/mL的植物乳杆菌LNL2-4-2菌悬液处理互隔交链孢霉孢子8 h后,其细胞膜完整性降低10.98%,胞外丙二醛、可溶性蛋白质、可溶性糖含量分别增加10.66%,3.10%,11.21%。超微结构分析表明:菌株LNL2-4-2导致互隔交链孢霉的孢子表面皱缩,边缘模糊,顶端破裂,内容物泄漏。在苹果生物防治研究中,贮藏6 d时,浓度为10^(3) CFU/mL的植物乳杆菌LNL2-4-2对互隔交链孢霉造成损伤的抑制率达47.24%。结论:植物乳杆菌LNL2-4-2可作为针对果蔬采后传统杀菌剂的新型替代品。

Black spot disease caused by Alternaria alternata is one of the main diseases of fruits and vegetables after harvest.The aims of this study were to screen lactic acid bacteria(LAB)with antagonistic activity to A.alternata,and to preliminarily explore the antibacterial mechanism of LAB.The strains with strong inhibitory activity against A.alternata was screened by fungus cake method,and it was identified by biochemical tests and 16S rDNA sequencing.The inhibition mechanism of L.plantarum was preliminarily investigated by the determination of cell membrane integrity,malondialdehyde,soluble protein,soluble sugar content,and spore ultrastructural changes.Results indicated that the strain LNL2-4-2 had a strong inhibitory effect on A.alternata,and the inhibition rate was 80.86%.It was identified as Lactobacillus plantarum.Different concentrations of strain LNL2-4-2 inhibited the growth of A.alternata mycelium and spore germination,and the inhibition effect increased with increasing concentration.When the concentration of strain LNL2-4-2 was 10^(9) CFU/mL,the membrane integrity rate of A.alternata spores decreased by 10.98%,and the extracellular malondialdehyde,soluble protein and soluble sugar content increased by 10.66%,3.10%and 11.21%,respectively.The scanning electron microscope images showed that strain LNL2-4-2 damaged A.alternata plasma membrane,resulting in spore surface to shrink,the edges to be blurred,and the top to disrupt.In the study of apple biological control,when stored for 6 days,the inhibition rate of LNL2-4-2 at a concentration of 10^(3) CFU/mL on the diameter of the damage caused by A.alternata reached 47.24%.These results indicated that the action site of L.plantarum LNL2-4-2 on A.alternata was cell membrane of spores,which exerted antagonism through membrane damage.The study proved that L.plantarum LNL2-4-2 can act as a biological preservative for inhibiting A.alternata.