Sterilisation technologies are essential to eliminate foodborne pathogens from food contact surfaces. However, most of the current sterilisation methods involve high energy and chemical consumption. In this study, a photodynamic inactivation coating featuring excellent antibacterial activity was prepared by dispersing curcumin as a plant-based photosensitiser in a chitosan solution. The coating generated abundant reactive oxygen species (ROS) after light irradiation at 420 nm, which eradicated ≥99.999 % of O157:H7. It was also found that ROS damaged the cell membrane, leading to the leakage of cell contents and cell shrinkage on the basis of chitosan. In addition, the production of ROS first excited the bacterial antioxidant defence system resulting in the increase of peroxidase (POD) and superoxide dismutase (SOD). ROS levels exceed its capacity, causing damage to the defence system and further oxidative decomposition of large molecules, such as DNA and proteins, eventually leading to the death of O157:H7. We also found the curcumin/chitosan coating could effectively remove O157:H7 biofilms by oxidative of extracellular polysaccharides and proteins. All the contributors made the chitosan/curcumin coating an efficient detergent comparable with HClO.

中文翻译：

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壳聚糖/姜黄素涂层对大肠杆菌 O157:H7 的增强光动力灭活及其在食品接触表面的应用

灭菌技术对于消除食品接触表面的食源性病原体至关重要。然而，目前大多数灭菌方法都涉及高能量和化学品消耗。在这项研究中，通过将姜黄素作为植物基光敏剂分散在壳聚糖溶液中，制备了具有优异抗菌活性的光动力灭活涂层。 420 nm 光照射后，涂层产生丰富的活性氧 (ROS)，消除了 ≥99.999 % 的 O157:H7。还发现ROS会损伤细胞膜，导致细胞内容物渗漏，在壳聚糖的基础上导致细胞皱缩。此外，ROS的产生首先刺激细菌抗氧化防御系统，导致过氧化物酶（POD）和超氧化物歧化酶（SOD）增加。 ROS水平超过其承受能力，导致防御系统受损，并进一步氧化分解DNA和蛋白质等大分子，最终导致O157:H7死亡。我们还发现姜黄素/壳聚糖涂层可以通过氧化细胞外多糖和蛋白质来有效去除 O157:H7 生物膜。所有贡献者都使壳聚糖/姜黄素涂层成为可与 HClO 相媲美的高效洗涤剂。