PDF(Pubmed)
Abstract：
Ultraviolet-C light-emitting diodes (UV-C LEDs) are an emerging technology for decontamination applications in different sectors. In this study, the inactivation of bacterial biofilms was investigated by applying an UV-C LED emitting at 280 nm and by measuring both the influence of the initial cell density (load) and presence of an extracellular matrix (biofilm). Two bacterial strains exposing diverging matrix structures and biochemical compositions were used: Pseudomonas aeruginosa and Leuconostoc citreum. UV-C LED irradiation was applied at three UV doses (171 to 684 mJ/cm2) on both surface-spread cells and on 24-h biofilms and under controlled cell loads, and bacterial survival was determined. All surface-spread bacteria, between 105 and 109 CFU/cm2, and biofilms at 108 CFU/cm2 showed that bacterial response to irradiation was dose-dependent. The treatment efficacy decreased significantly for L. citreum surface-spread cells when the initial cell load was high, while no load effect was observed for P. aeruginosa. Inactivation was also reduced when bacteria were grown under a biofilm form, especially for P. aeruginosa: a protective effect could be attributed to abundant extracellular DNA and proteins in the matrix of P. aeruginosa biofilms, as revealed by Confocal Laser Scanning Microscopy observations. This study showed that initial cell load and exopolymeric substances are major factors influencing UV-C LED antibiofilm treatment efficacy. KEY POINTS: • Bacterial cell load (CFU/cm2) could impact UV-C LED irradiation efficiency • Characteristics of the biofilm matrix have a paramount importance on inactivation • The dose to be applied can be predicted based on biofilm properties.
摘要：
紫外线C发光二极管（UV-CLED）是一种新兴的技术，用于不同领域的净化应用。在这项研究中,通过应用在280nm处发射的UV-CLED并通过测量初始细胞密度(负载)和细胞外基质(生物膜)的存在的影响来研究细菌生物膜的失活。使用了两种暴露不同基质结构和生化成分的细菌菌株：铜绿假单胞菌和褐藻。UV-CLED照射以三种UV剂量（171至684mJ/cm2）施加在表面铺展细胞和24小时生物膜上，并在受控细胞负载下，并确定了细菌的存活率。所有表面传播的细菌，在105和109CFU/cm2之间，生物膜在108CFU/cm2表明细菌对辐射的反应是剂量依赖性的。当初始细胞负载较高时，对柠檬酸乳杆菌表面铺展细胞的治疗功效显着下降，而铜绿假单胞菌无负荷效应。当细菌在生物膜形式下生长时，失活也会减少，特别是对于铜绿假单胞菌：保护作用可归因于铜绿假单胞菌生物膜基质中丰富的细胞外DNA和蛋白质，共聚焦激光扫描显微镜观察显示。这项研究表明，初始细胞负载和胞外聚合物是影响UV-CLED抗生物膜治疗功效的主要因素。关键点:•细菌细胞负荷(CFU/cm2)可影响UV-CLED照射效率•生物膜基质的特性对于灭活具有最重要的意义•可基于生物膜特性来预测要施加的剂量。
