壳聚糖/姜黄素光动力复合涂膜对金黄色葡萄球菌的抑菌效果及机理

Antibacterial Effect and Mechanism of Chitosan/Curcumin Composite Photodynamic Coating on Staphylococcus aureus

本研究采用壳聚糖为原料,利用离子相互作用增强姜黄素光动力抑菌效果,并从形态特征、细胞膜功能、能量代谢和DNA结构等方面入手阐释该涂膜在细胞水平上对金黄色葡萄球菌的抑菌机理。结果表明,壳聚糖显著提高了抑菌效果,含姜黄素质量浓度15 mg/L的涂膜溶液经波长为420 nm蓝光光照5 min后,金黄色葡萄球菌菌落总数下降6.89(lg(CFU/mL)),并且姜黄素质量浓度和光照时间是影响该技术抑菌效果的主要因素。光动力灭活处理产生具有强氧化性的活性氧从而破坏细胞膜,促使细胞膜通透性增加,进而出现细胞内容物泄漏以及细胞皱缩的现象。同时也导致细胞内活性氧含量上升,破坏内源酶结构,引发细菌防御系统崩溃,DNA和蛋白质等大分子被氧化分解,从而导致金黄色葡萄球菌死亡。由此可见,壳聚糖/姜黄素光动力涂膜有应用于控制金黄色葡萄球菌食源性污染的潜力。

In this study,chitosan was used to enhance the photodynamic antibacterial effect of curcumin through ionic interactions,and the antibacterial mechanism of this coating against Staphylococcus aureus at the cellular level was clarified from the aspects of morphological characteristics,cell membrane function,energy metabolism,and DNA structure.The results showed that chitosan significantly improve the antibacterial effect.The number of S.aureus decreased by 6.89(lg(CFU/mL))after the coating solution containing 15 mg/L curcumin was exposed to 420 nm blue light for 5 min.Curcumin concentration and illumination time were the major factors affecting the antibacterial effect of this technique.The photodynamic inactivation treatment produced highly oxidizing reactive oxygen species(ROS),damaging the cell membrane and increasing membrane permeability,thus leading to the leakage of cell contents and cell shrinkage.It also led to an increase in intracellular ROS levels,which disrupted the structure of endogenous enzymes to trigger the breakdown of the bacterial defense system and the oxidative decomposition of macromolecules such as DNA and proteins,eventually causing the death of S.aureus.Therefore,chitosan/curcumin photodynamic coating has application potential in controlling foodborne pollution of S.aureus.