Faculty of Agricultural Sciences, Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India.
Zoology Department, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
J Microbiol Methods. 2019 Nov;166:105716. doi: 10.1016/j.mimet.2019.105716. Epub 2019 Sep 6.
We provide a novel one-step/one-pot bio-inspired method of synthesis for Myristica fragrans leaf ester (MFLE) capped‑zinc oxide nanoparticles (MFLE-ZnONPs). Antibacterial and antbiofilm efficacies of MFLE-ZnONPs were tested against the multi-drug resistant (MDR) Escherichia coli (E. coli-336), methicillin-resistant Staphylococcus aureus (MRSA-1) and methicillin-sensitive (MSSA-2) clinical isolates. Antibacterial screening using well diffusion assay revealed the cytotoxicity of MFLE-ZnONPs in the range of 500-2000 μg/ml. MFLE-ZnONPs significantly increased the zone of growth inhibition of E. coli-336 (17.0 ± 0.5 to 19.25 ± 1.0 mm), MSSA-2 (16.75 ± 0.8 to 19.0 ± 0.7 mm) and MRSA-1 (16.25 ± 1.0 to 18.25 ± 0.5 mm), respectively. The minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) against E. coli-336, MRSA-1 and MSSA-2 were found to be 1500, 1000 and 500 μg/ml, and 2500, 2000 and 1500 μg/ml, respectively. A time and dose dependent reduction in the cell proliferation were also found at the respective MICs of tested strains. Scanning electron microscopy (SEM) of MFLE-ZnONPs-treated strains exhibited cellular damage via loss of native rod and coccoid shapes because of the formation of pits and cavities. E. coli-336 and MRSA-1 strains at their MICs (1500 and 1000 μg/ml) sharply reduced the biofilm production to 51% and 24%. The physico-chemical characterization via x-ray diffraction (XRD) ascertained the crystallinity and an average size of MFLE-ZnONPs as 48.32 ± 2.5 nm. Gas chromatography-mass spectroscopy (GC-MS) analysis of MFLE-ZnONPs unravelled the involvement of two bio-active esters (1) butyl 3-oxobut-2-yl ester and (2) α-monoolein) as surface capping/stabilizing agents. Fourier transform infrared (FTIR) analysis of MFLE and MFLE-ZnONPs showed the association of amines, alkanes, aldehydes, amides, carbonyl and amines functional groups in the corona formation. Overall, our data provide novel insights on the rapid development of eco-friendly, cost-effective bio-synthesis of MFLE-ZnONPs, showing their putative application as nano-antibiotics against MDR clinical isolates.
我们提供了一种新颖的一步/一锅仿生合成方法，用于合成肉豆蔻叶酯（MFLE）封端的氧化锌纳米粒子（MFLE-ZnONPs）。我们测试了 MFLE-ZnONPs 对多药耐药（MDR）大肠杆菌（E. coli-336）、耐甲氧西林金黄色葡萄球菌（MRSA-1）和甲氧西林敏感（MSSA-2）临床分离株的抗菌和抗生物膜功效。使用孔扩散法进行的抗菌筛选显示，MFLE-ZnONPs 的细胞毒性范围为 500-2000μg/ml。MFLE-ZnONPs 显著增加了 E. coli-336（17.0±0.5 至 19.25±1.0mm）、MSSA-2（16.75±0.8 至 19.0±0.7mm）和 MRSA-1（16.25±1.0 至 18.25±0.5mm）的生长抑制区。对 E. coli-336、MRSA-1 和 MSSA-2 的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）分别发现为 1500、1000 和 500μg/ml 和 2500、2000 和 1500μg/ml。在测试菌株的相应 MIC 下，还发现细胞增殖呈时间和剂量依赖性减少。经 MFLE-ZnONPs 处理的菌株的扫描电子显微镜（SEM）显示，由于形成凹坑和空穴，细胞形态发生了原生棒状和球形的丧失，从而导致细胞损伤。E. coli-336 和 MRSA-1 菌株在其 MIC（1500 和 1000μg/ml）下，生物膜的产生急剧减少至 51%和 24%。通过 X 射线衍射（XRD）进行的物理化学特性表征确定了 MFLE-ZnONPs 的结晶度和平均尺寸为 48.32±2.5nm。MFLE-ZnONPs 的气相色谱-质谱联用（GC-MS）分析揭示了两种生物活性酯（1）丁基 3-氧代丁-2-基酯和（2）α-单油酸甘油酯）作为表面封端/稳定化剂的参与。MFLE 和 MFLE-ZnONPs 的傅里叶变换红外（FTIR）分析表明，胺、烷烃、醛、酰胺、羰基和胺官能团在冠形成中存在关联。总的来说，我们的数据提供了关于生态友好、经济高效的 MFLE-ZnONPs 生物合成的快速发展的新见解，表明它们可能作为纳米抗生素应用于多药耐药临床分离株。
