Biofilm formation by Pseudomonas aeruginosa contributes to its survival on surfaces and represents a major clinical threat because of the increased tolerance of biofilms to disinfecting agents. This study aimed to investigate the efficacy of 405-nm light-emitting diode (LED) illumination in eliminating P. aeruginosa biofilms formed on stainless steel coupons under different temperatures. Time-dependent killing assays using planktonic and biofilm cells were used to determine the antimicrobial and antibiofilm activity of LED illumination. We also evaluated the effects of LED illumination on the disinfectant susceptibility, biofilm structure, extracellular polymeric substance (EPS) structure and composition, and biofilm-related gene expression of P. aeruginosa biofilm cells. Results showed that the abundance of planktonic P. aeruginosa cells was reduced by 0.88, 0.53, and 0.85 log CFU/mL following LED treatment for 2 h compared with untreated controls at 4, 10, and 25°C, respectively. For cells in biofilms, significant reductions (1.73, 1.59, and 1.68 log CFU/cm²) were observed following LED illumination for 2 h at 4, 10, and 25°C, respectively. Moreover, illuminated P. aeruginosa biofilm cells were more sensitive to benzalkonium chloride or chlorhexidine compared with untreated cells. Scanning electron microscopy and confocal laser scanning microscopic observation indicated that both the biofilm structure and EPS structure were disrupted by LED illumination. Further, reverse transcription-quantitative PCR revealed that LED illumination downregulated the transcription of several genes associated with biofilm formation. These findings suggest that LED illumination has the potential to be developed as an alternative method for prevention and control of P. aeruginosa biofilm contamination.

Importance:

Pseudomonas aeruginosa can form biofilms on medical implants, industrial equipment, and domestic surfaces, contributing to its high morbidity and mortality rates. This study examined the antibiofilm activity of 405-nm light-emitting diode (LED) illumination against mature biofilms formed on stainless steel coupons. We found that the disinfectant susceptibility, biofilm structure, and extracellular polymeric substance structure and composition were disrupted by LED illumination. We then investigated the transcription of several critical P. aeruginosa biofilm-related genes and analyzed the effect of illumination temperature on the above characteristics. Our results confirmed that LED illumination could be developed into an effective and safe method to counter P. aeruginosa biofilm contamination. Further research will be focused on the efficacy and application of LED illumination for elimination of complicated biofilms in the environment.

铜绿假单胞菌形成的生物膜有助于其在表面上的存活，并且由于生物膜对消毒剂的耐受性增强而代表了主要的临床威胁。这项研究旨在研究405 nm发光二极管（LED）照明在消除不同温度下不锈钢试样上形成的铜绿假单胞菌生物膜的功效。使用浮游生物和生物膜细胞的时间依赖性杀灭测定被用于确定LED照明的抗微生物和抗生物膜活性。我们还评估了LED照明对铜绿假单胞菌消毒剂敏感性，生物膜结构，细胞外聚合物（EPS）的结构和组成以及生物膜相关基因表达的影响。生物膜细胞。结果显示，与未处理的对照组相比，分别在4、10和25°C下进行LED处理2 h后，浮游铜绿假单胞菌细胞的丰度分别降低了0.88、0.53和0.85 log CFU / mL。对于生物膜中的细胞，分别在4、10和25°C下LED照明2 h后，观察到显着降低（1.73、1.59和1.68 log CFU / cm ²）。此外，照明的铜绿假单胞菌与未处理的细胞相比，生物膜细胞对苯扎氯铵或洗必泰更敏感。扫描电子显微镜和共聚焦激光扫描显微镜观察表明，LED照明破坏了生物膜结构和EPS结构。此外，逆转录定量PCR显示，LED照明下调了与生物膜形成相关的几个基因的转录。这些发现表明，LED照明有可能被开发为预防和控制铜绿假单胞菌生物膜污染的替代方法。

重要性：

铜绿假单胞菌可在医疗植入物，工业设备和家庭表面上形成生物膜，从而导致其高发病率和死亡率。这项研究检查了405 nm发光二极管（LED）照明对不锈钢试样上形成的成熟生物膜的抗生物膜活性。我们发现，LED照明破坏了消毒剂的敏感性，生物膜结构以及细胞外聚合物的结构和组成。然后，我们调查了几个关键的铜绿假单胞菌生物膜相关基因的转录，并分析了照明温度对上述特征的影响。我们的结果证实，LED照明可以发展成为一种对抗铜绿假单胞菌的有效且安全的方法。生物膜污染。进一步的研究将集中在消除环境中复杂生物膜的LED照明的功效和应用上。