Objective To investigate the broad-spectrum antibacterial efficacy of chitosan ( CHI ) and its derivatives. Methods The antibacterial test of Pseudomonas aeruginosa was performed by CHI and quaternized chitosan ( QCHI). The volumes of per 1 mL at 0, 3, 6, 9 and 12 h by CHI and QCHI were determined. The results were compared with those of control hole volume. The Pseudomonas aeruginosa RNA was extracted simultaneously. The ahpF, pa3187, aprA and rpoS genes were amplified, and their expressions were determined. The remaining Pseudomonas aeruginosa were cultured by LB medium for 3 d. The floating bacteria were flushed by PBS buffer solution, and were stained by crystallization violet. After decolorizing by 95% ethanol, the biofilm formation function of Pseudomonas aeruginosa was analyzed by enzyme-labeled analyzer at 570 nm. Results There were significant differences between CHI and QCHI hole volumes of live bacteria after culturing 6 h compared with control hole volumes, but there was no obvious difference CHI and QCHI volumes. The pa3187 expression was increased by CHI and QCHI, but aprA expression was decreased by them. QCHI can decrease ahpF expression, but CHI can improve ahpF expression. The rpoS expression was also decreased by QCHI. Biofilm formation showed that the significant inhibitory effect could be seen in Pseudomonas aeruginosa biofilm formation by CHI and QCHI from culturing 6 h. Conclusions In a certain extent, CHI and QCHI can inhibit the proliferation and biofilm formation of Pseudomonas aeruginosa.%目的 探讨壳聚糖(CHI)及其衍生物可能具有的广谱抗菌作用.方法 采用CHI、壳聚糖季铵盐(QCHI)进行铜绿假单胞菌体外抑菌试验.采用CHI和QCHI分别作用0、3、6、9、12 h,每个时间点取1 mL菌液进行菌落计数并与对照孔比较,同时抽提铜绿假单胞菌RNA,扩增其ahpF、pa3187、aprA和rpoS基因,并检测各基因表达水平;剩余铜绿假单胞菌用LB培养基培养3 d,PBS缓冲液冲洗浮游细菌,结晶紫染色,95%乙醇脱色后用酶标仪570 nm检测并比较铜绿假单胞菌生物膜的形成能力.结果 与对照孔比较,自6 h起CHI和QCHI孔的存活菌量即有明显差异(P<0.05);但CHI孔和QCHI孔之间差异无统计学意义.CHI和QCHI均可使铜绿假单胞菌pa3187基因表达上调,aprA基因表达下调;QCHI可使ahpF基因表达下调,而CHI可使ahpF基因表达上调;QCHI对rpoS基因的表达有下调趋势.从6 h起,CHI和QCHI对铜绿假单胞菌生物膜的形成均有明显的抑制作用.结论 CHI及QCHI能在一定程度上抑制铜绿假单胞菌的增殖及其生物膜的形成.
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