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Abstract：
Pseudomonas aeruginosa is a commonly found Gram-negative bacterium in healthcare facilities and is renowned for its ability to form biofilms and its virulence factors that are controlled by quorum sensing (QS) systems. The increasing prevalence of multidrug-resistant strains of this bacterium poses a significant challenge in the field of medicine. Consequently, the exploration of novel antimicrobial agents has become a top priority. This research aims to optimize chitosan derived from white shrimp (Metapenaeus affinis) using the Response Surface Methodology (RSM) computational approach. The objective is to investigate chitosan\'s potential as a solution for inhibiting QS activity and biofilm formation in P. aeruginosa ATCC 10,145. Under optimized conditions, chitin was treated with NaOH (1.41 M) for 15.75 h, HCl (7.49% vol) for 2.01 h, and at a deacetylation temperature of 81.15 °C. The resulting chitosan exhibited a degree of deacetylation (DD%) exceeding 93.98%, as confirmed by Fourier-transform infrared (FTIR) spectral analysis, indicating its high purity. The extracted chitosan demonstrated a significant synergistic antibiotic effect against P. aeruginosa when combined with ceftazidime, enhancing its bactericidal activity by up to 15-fold. In addition, sub-MIC (minimum inhibitory concentration) concentrations of extracted chitosan (10 and 100 µg/mL) successfully reduced the production of pyocyanin and rhamnolipid, as well as the swimming motility, protease activity and biofilm formation ability in comparison to the control group (P < 0.05). Moreover, chitosan treatment downregulated the RhlR and LasR genes in P. aeruginosa when compared to the control group (P < 0.05). The optimized chitosan extract shows significant potential as a coating agent for surgical equipment, effectively preventing nosocomial infections caused by P. aeruginosa pathogens.
摘要：
铜绿假单胞菌是医疗保健机构中常见的革兰氏阴性细菌，以其形成生物膜的能力及其由群体感应（QS）系统控制的毒力因子而闻名。这种细菌的多重耐药菌株的日益流行在医学领域提出了重大挑战。因此,新型抗菌药物的探索已成为当务之急。本研究旨在使用响应面法（RSM）计算方法优化来自白虾（Metapenaeusaffinis）的壳聚糖。目的是研究壳聚糖作为抑制铜绿假单胞菌ATCC10,145中QS活性和生物膜形成的解决方案的潜力。在优化条件下，几丁质用NaOH（1.41M）处理15.75h，盐酸(7.49%vol)2.01h,和81.15℃的脱乙酰温度。得到的壳聚糖的脱乙酰度（DD％）超过93.98％，通过傅里叶变换红外(FTIR)光谱分析证实，表明其高纯度。当与头孢他啶联合使用时，提取的壳聚糖对铜绿假单胞菌具有明显的协同抗生素作用，将其杀菌活性提高15倍。此外,亚MIC（最低抑制浓度）浓度的提取的壳聚糖（10和100µg/mL）成功地减少了生成的绿脓苷和鼠李糖脂，以及游泳的运动性，蛋白酶活性和生物膜形成能力与对照组比较(P<0.05)。此外，与对照组相比，壳聚糖处理下调了铜绿假单胞菌的RhlR和LasR基因（P<0.05）。优化的壳聚糖提取物显示出作为手术设备涂层剂的巨大潜力，有效预防铜绿假单胞菌病原菌引起的医院感染。
