Plantaricin 163对热杀索丝菌的抗菌活性及其作用机制

Antibacterial activity and mechanism of action of Plantaricin 163 against Brochothrix thermosphacta

摘要:

【背景】热杀索丝菌(Brochothrix thermosphacta)为鲫鱼在4 °C贮藏过程中的主要腐败菌，Plantaricin 163是由植物乳杆菌产生的一种新型广谱细菌素，能明显延长鲫鱼的贮藏期。【目的】研究Plantaricin 163对热杀索丝菌的抗菌活性和作用机制。【方法】通过测定最小抑菌浓度(Minimum inhibitory concentration)和杀菌动力学了解Plantaricin 163对热杀索丝菌的抗菌效果，并从电导率的变化、核酸和蛋白的泄露、流式细胞实验、扫描电镜和透射电镜观察等4个方面探讨Plantaricin 163对热杀索丝菌的作用机制。【结果】Plantaricin 163对热杀索丝菌的的最小抑菌浓度为32 mg/mL，优于nisin的作用效果，作用方式为杀菌模式，6 h内能完全杀死热杀索丝菌。Plantaricin 163能够通过增加热杀索丝菌细胞膜的通透性，增加胞外电导率，进而破坏细胞膜完整性，导致内容物泄漏，并影响细胞的外部形态和内部结构，从而导致菌体细胞瓦解死亡。【结论】Plantaricin 163可以破坏热杀索丝菌的细胞膜和内部结构，发挥抗菌活性。

Abstract:

[Background] Brochothrix thermosphacta is the main spoilage bacterium in Crucian Carp (Carassius auratus) during storage at 4 °C. Plantaricin 163, a new broad-spectrum bacteriocin produced by Lactobacillus plantarum, significantly extends the shelf life of crucian carp. [Objective] To investigate the antibacterial activity and mechanism of action of Plantaricin 163 against B. thermosphacta. [Methods] The minimum inhibitory concentration and bactericidal kinetics of Plantaricin 163 were determined to measure the antimicrobial effect of Plantaricin 163 on B. thermosphacta. Change in conductivity, and nucleic acid and protein leakage were measured, and flow cytometry, scanning electron microscopy, and transmission electron microscopy were performed, to determine the mechanism of action of Plantaricin 163 against B. thermosphacta. [Results] The MIC of Plantaricin 163 against B. thermosphacta was found to be 32 μg/mL, which was better than that of nisin, and the mode of action of the bacteriocin was killing of cells instead of growth inhibition. The permeability of the cell membrane was increased and caused a change in extracellular conductivity, thereby destroying the integrity of the cell membrane and resulting in the leakage of cell contents. The external morphology and internal structure of the cells were affected, eventually leading to cell death. [Conclusion] Plantaricin 163 can destroy the membrane and internal structure of B. thermosphacta.