背景:Hormesis描述了一种反剂量-反应关系,高剂量的有毒化合物具有抑制作用,低剂量是有刺激性的.本研究探讨了低浓度氧化锌纳米颗粒(ZnONPs)对铜绿假单胞菌的封闭反应。
方法:铜绿假单胞菌样品,即参考应变,ATCC27,853,以及从囊性纤维化患者中恢复的六株菌株,暴露于10个递减的ZnONPs剂量(0.78-400µg/mL)。ZnONPs是使用化学绿色合成方法从Peganumharmala制备的,并利用X射线衍射和扫描电子显微镜对其性能进行了验证。采用微量滴定板技术研究了ZnONPs对生长的影响,铜绿假单胞菌生物膜的形成和代谢活性。进行实时聚合酶链反应以确定ZnONPs对七个生物膜编码基因表达的影响。
结果:在100-400µg/mL的浓度下,ZnONP表现出浓度依赖性杀菌和抗生物膜效率。然而,在ZnONPs浓度为25µg/mL(ATCC27853,Pa3和Pa4)以及12.5µg/mL和6.25µg/mL(ATCC27853,Pa2,Pa4和Pa5)时,显着刺激了生长。在稀释度<6.25μg/mL时未检测到显著的正生长。同样,在12.5µg/mL(ATCC27853和Pa1)和6.25µg/mL(Pa4)的浓度下刺激生物膜形成。浓度为12.5µg/mL时,ZnONPs上调了LasB(ATCC27853,Pa1和Pa4)和LasR和LasI(ATCC27853和Pa1)的表达以及RhII(ATCC27853,Pa2和Pa4)的表达。
结论:当暴露于低ZnONPs浓度时,铜绿假单胞菌表现得很恐怖,正生长和生物膜形成。这些结果突出了理解铜绿假单胞菌在暴露于低ZnONPs浓度后的响应的重要性。
BACKGROUND: Hormesis describes an inverse dose-response relationship, whereby a high dose of a toxic compound is inhibitory, and a low dose is stimulatory. This study explores the hormetic response of low concentrations of zinc oxide nanoparticles (ZnO NPs) toward Pseudomonas aeruginosa.
METHODS: Samples of P. aeruginosa, i.e. the reference strain, ATCC 27,853, together with six strains recovered from patients with cystic fibrosis, were exposed to ten decreasing ZnO NPs doses (0.78-400 µg/mL). The ZnO NPs were manufactured from Peganum harmala using a chemical green synthesis approach, and their properties were verified utilizing X-ray diffraction and scanning electron microscopy. A microtiter plate technique was employed to investigate the impact of ZnO NPs on the growth, biofilm formation and metabolic activity of P. aeruginosa. Real-time polymerase chain reactions were performed to determine the effect of ZnO NPs on the expression of seven biofilm-encoding genes.
RESULTS: The ZnO NPs demonstrated concentration-dependent bactericidal and antibiofilm efficiency at concentrations of 100-400 µg/mL. However, growth was significantly stimulated at ZnO NPs concentration of 25 µg/mL (ATCC 27853, Pa 3 and Pa 4) and at 12.5 µg/mL and 6.25 µg/mL (ATCC 27853, Pa 2, Pa 4 and Pa 5). No significant positive growth was detected at dilutions < 6.25 µg/mL. similarly, biofilm formation was stimulated at concentration of 12.5 µg/mL (ATCC 27853 and Pa 1) and at 6.25 µg/mL (Pa 4). At concentration of 12.5 µg/mL, ZnO NPs upregulated the expression of LasB ( ATCC 27853, Pa 1 and Pa 4) and LasR and LasI (ATCC 27853 and Pa 1) as well as RhII expression (ATCC 27853, Pa 2 and Pa 4).
CONCLUSIONS: When exposed to low ZnO NPs concentrations, P. aeruginosa behaves in a hormetic manner, undergoing positive growth and biofilm formation. These results highlight the importance of understanding the response of P. aeruginosa following exposure to low ZnO NPs concentrations.